Pull the stove out enough to reach the back where the vent pipe is located.
Loosen the screws holding the pressure clamp in place and carefully slide the vent pipe off the stove. This is the flexible part of the pipe.
Set up your ladder and carefully climb to the roof. Locate the vent pipe.
Unscrew the vent pipe’s pressure clamp that is holding it onto the roof.
Pull the vent pipe up through the vent shaft with someone's assistance. Go slowly to avoid tearing the flexible pipe.
Transfer the vent pipe to the ground and carefully climb off the ladder.
Pull apart the vent pipe pieces on the ground and clean each component thoroughly with a pipe brush.