Removing a lawn mower spark plug may seem like a daunting task, but it's actually quite simple. All you need is a ratchet and the appropriate size socket. Start by disconnecting the spark plug wire from the spark plug. Next, use the ratchet to loosen the spark plug until it can be removed by hand. Be careful not to drop the spark plug, as this could damage the threads. Finally, clean the area around the spark plug hole before installing the new spark plug. Make sure to use the correct size socket when tightening the new spark plug, as overtightening could damage the engine. With just a few simple tools, you can remove and replace a lawn mower spark plug in no time.