Allow the RTV to sit after use and cool down. The exhaust system and the muffler will be too hot to touch right after use.
Spray down the muffler and the exhaust pipes on the back of the tractor with a garden hose to cool them down more.
Remove the two bolts holding the muffler to the exhaust pipe with a wrench. Slide the muffler away from the mounting bracket on the bottom of the RTV using your hands.
Spray the muffler down with a rust cleaner and use a rag to clean the inside of the unit. This dirt buildup will raise the pressure and temperature in the engine.
Fill a container with water, then add a couple drops of soap and bleach it. Allow the muffler to sit in the solution overnight. Hose the muffler down in the morning, then reattach it to your RTV.