Gather a pedal wrench or 15 mm wrench, and a bike stand or a way to stabilize the bike
Shift the chain onto the smallest chainring and smallest rear cog if needed for clearance
Identify the pedal threads: right pedal loosens counterclockwise, left pedal loosens clockwise
Position the crank arm so the pedal wrench is horizontal and easy to push
Place the wrench on the pedal flats firmly
Turn the wrench in the loosening direction
Use steady force to break the pedal free
Remove the pedal by hand once it is loose
Repeat on the other side, remembering the opposite thread on the left pedal
Apply penetrating oil and wait if the pedal is stuck
Use a longer wrench or more leverage if needed
Clean the threads after removal
Apply grease before reinstalling pedals later