How to Clean a Charcoal Grill
Out of the many different types of grills, the varieties that heat using charcoal require the most cleaning. Keep charcoal grills in peak condition by cleaning them during, before and after grill season. Here’s how.
Charcoal ash gathers at the bottom of the grill every time it's used. Built-up ash can block vents in the bottom of the grill. This will make it difficult to control cooking temperature and increase fire risks.   
Once the charcoal has cooled, remove the bricks and brush out the ash.  
Cleaning grill grates is best done with a long-handled, stiff-wire brush. If you don’t have a brush, ball up some aluminum foil. Hold it with long-handled tongs.  
Use a rag or folded paper towels to apply vegetable oil to the clean grates. This will help prevent rust and food build-up.  
Clean the inside of the grilling bowl and lid using mild dish soap and a steel brush.  
Keep your charcoal grill in peak condition with regular maintenance before and after grilling season. Follow these cleaning tips at the beginning and end of each grilling season. 
Clean the outside of the lid and bowl with soap and water or grill cleaner. 
Towel dry to prevent rust.  

How to Clean a Gas Grill
Natural gas or propane-powered gas grills don’t require the level of cleaning required of charcoal grills. However, they should be thoroughly cleaned at the beginning and end of each grilling season. Doing this will help remove grease and smoke buildup. 
After each use:  
Cleaning grill grates is easier with a long-handled, stiff-wire brush. 
Use a rag or folded paper towels to apply vegetable oil to the clean grill grates. This will help prevent rust and food build-up. 
Clean the inside of the grilling lid using mild dish soap and a steel brush.  
Remove the heat deflectors located over the burners and wash with dish soap and water. 
Dry thoroughly with a rag.

How to Clean a Flat Top Grill
Flat top grills are more commonly used in commercial spaces, but they can be a great addition to your backyard setup. They don’t have regular grill grates, so use a different method to clean them. 
Start cleaning the surface while the burner is still hot. Use caution to avoid getting burnt from the steam.
Spray a cleaning solution along the top and let it sit for about 1 minute. You can use dish soap, a degreaser or a homemade baking soda mixture.
Use a grill brush to scrub away any stuck-on food and debris.
Wipe it down with a dry cloth and repeat the process as needed.

How to Clean a Pellet Grill
Make sure the pellet smoker has completely cooled before cleaning a pellet grill.
Remove the grill grates and place them in a bucket of warm, soapy water.
Take a wet-dry vac and clear out the ash and debris from the grill’s interior. 
Use a scrub brush or abrasive sponge to clean the drip pan.
Remove the chimney cap and clean the inside with a scrub brush. 
Wipe down all parts with a damp cloth.

How to Deep Clean Grill Grates
If your grill grates are still dirty after a regular scrubbing session, it’s likely time for a deep clean. Soak them in a mixture of vinegar and baking soda. Together, these ingredients break down any stuck-on food. See below for more specifics on cleaning different types of grill grates:
Stainless steel grill grates are generally the easiest to clean. Cover the top with aluminum foil and let the grill heat up for about 15 minutes. This should burn off the remaining food bits and make it easier to scrub once they’ve cooled down.
For porcelain grill grates, try to burn off any lingering bits of food. Then let them cool completely. Remove them and use a nylon or soft bristle brush to scrub the surface. Don’t use a brush with wire or metal bristles, as those will damage the surface.
For cast iron grill grates, burn off any lingering bits of food. Once they’re cool, use a soft bristle brush to scrub any remaining debris, using minimal water to prevent rust. Finish them off with a light coating of vegetable oil.

Grill Cleaning Tips
When cleaning grills with bristle brushes and other grill cleaning tools, always thoroughly wipe down the cleaned area afterwards. This will remove any bristles that may have come off during the cleaning process and get stuck to the grill. 
Except for flat tops, the best way to clean a grill is to start while the grilling surface is warm. Make sure to wait until the surface has cooled enough that it will not burn you.
Keep the grill protected with a grill cover.  
Replace your grill brush annually.

SOURCE: homedepot.com

How to Clean a Charcoal Grill
Out of the many different types of grills, the varieties that heat using charcoal require the most cleaning. Keep charcoal grills in peak condition by cleaning them during, before and after grill season. Here’s how.
Charcoal ash gathers at the bottom of the grill every time it's used. Built-up ash can block vents in the bottom of the grill. This will make it difficult to control cooking temperature and increase fire risks.   
Once the charcoal has cooled, remove the bricks and brush out the ash.  
Cleaning grill grates is best done with a long-handled, stiff-wire brush. If you don’t have a brush, ball up some aluminum foil. Hold it with long-handled tongs.  
Use a rag or folded paper towels to apply vegetable oil to the clean grates. This will help prevent rust and food build-up.  
Clean the inside of the grilling bowl and lid using mild dish soap and a steel brush.  
Keep your charcoal grill in peak condition with regular maintenance before and after grilling season. Follow these cleaning tips at the beginning and end of each grilling season. 
Clean the outside of the lid and bowl with soap and water or grill cleaner. 
Towel dry to prevent rust.  

How to Clean a Gas Grill
Natural gas or propane-powered gas grills don’t require the level of cleaning required of charcoal grills. However, they should be thoroughly cleaned at the beginning and end of each grilling season. Doing this will help remove grease and smoke buildup. 
After each use:  
Cleaning grill grates is easier with a long-handled, stiff-wire brush. 
Use a rag or folded paper towels to apply vegetable oil to the clean grill grates. This will help prevent rust and food build-up. 
Clean the inside of the grilling lid using mild dish soap and a steel brush.  
Remove the heat deflectors located over the burners and wash with dish soap and water. 
Dry thoroughly with a rag.

How to Clean a Flat Top Grill
Flat top grills are more commonly used in commercial spaces, but they can be a great addition to your backyard setup. They don’t have regular grill grates, so use a different method to clean them. 
Start cleaning the surface while the burner is still hot. Use caution to avoid getting burnt from the steam.
Spray a cleaning solution along the top and let it sit for about 1 minute. You can use dish soap, a degreaser or a homemade baking soda mixture.
Use a grill brush to scrub away any stuck-on food and debris.
Wipe it down with a dry cloth and repeat the process as needed.

How to Clean a Pellet Grill
Make sure the pellet smoker has completely cooled before cleaning a pellet grill.
Remove the grill grates and place them in a bucket of warm, soapy water.
Take a wet-dry vac and clear out the ash and debris from the grill’s interior. 
Use a scrub brush or abrasive sponge to clean the drip pan.
Remove the chimney cap and clean the inside with a scrub brush. 
Wipe down all parts with a damp cloth.

How to Deep Clean Grill Grates
If your grill grates are still dirty after a regular scrubbing session, it’s likely time for a deep clean. Soak them in a mixture of vinegar and baking soda. Together, these ingredients break down any stuck-on food. See below for more specifics on cleaning different types of grill grates:
Stainless steel grill grates are generally the easiest to clean. Cover the top with aluminum foil and let the grill heat up for about 15 minutes. This should burn off the remaining food bits and make it easier to scrub once they’ve cooled down.
For porcelain grill grates, try to burn off any lingering bits of food. Then let them cool completely. Remove them and use a nylon or soft bristle brush to scrub the surface. Don’t use a brush with wire or metal bristles, as those will damage the surface.
For cast iron grill grates, burn off any lingering bits of food. Once they’re cool, use a soft bristle brush to scrub any remaining debris, using minimal water to prevent rust. Finish them off with a light coating of vegetable oil.

Grill Cleaning Tips
When cleaning grills with bristle brushes and other grill cleaning tools, always thoroughly wipe down the cleaned area afterwards. This will remove any bristles that may have come off during the cleaning process and get stuck to the grill. 
Except for flat tops, the best way to clean a grill is to start while the grilling surface is warm. Make sure to wait until the surface has cooled enough that it will not burn you.
Keep the grill protected with a grill cover.  
Replace your grill brush annually.

SOURCE: homedepot.com