Here are the general steps to change a bicycle tire:
Turn the bike upside down or place it on a bike stand so that the rear wheel is off the ground.
Use a tire lever to pry the tire away from the rim. Insert the lever between the tire and the rim, and slide it around the circumference of the tire, gradually prying it away from the rim.
Once you have pried one side of the tire off the rim, remove the inner tube from the tire.
Check the tire for any damage or debris that might have caused the flat, and remove it if necessary.
