Get your tire levers from your tool kit - you will need at least two

Fully deflate your inner tube by pressing down on the valve; this will make it easier to remove

Insert one lever under the tire bead, on the opposite side of the valve; some tire levers have a hook on the end that can be attached to a spoke to keep it in place

Insert the other lever about 5-10 cm away

Pry the bead up and over the rim by working the levers both at once

Slide one lever around the edge of the rim and pull out the tube all around, ending at the valve.

With your fingers, reach inside the tire and pull out the tube all around, ending at the valve

Carefully pull the valve stem out of the rim hole (if there is a lock nut, remove it first)