Position the mower on a level surface. Slide a jack underneath the front or back of the lawn mower, depending on the tire's location. Jack the mower up high enough so that the tire is a few inches off the ground. Place a wood block underneath the mower to hold it steady.
Pry off the wheel's hub cap using a flat-head screwdriver.
Grip the curved, bent end of the spring clip with a pair of needle-nose pliers and bend it straight. Hold the wheel with one hand, to keep it from moving, and wiggle the clip with the pliers, if necessary, to remove it from the hole.