Just as you have to top up the oil and gasoline in your lawnmower, on occasion you will have to remove the blade. Removing the blade of your lawn mower allows you to remove thick, hard grass from under the mowing deck, sharpen the blade and reposition it when it begins to turn unevenly. Removing a blade correctly is easy to do, but it will require a bit of concentration to prevent injuries to yourself or damage to the machine.
Put on a thick pair of work gloves and safety glasses to prevent scrapes to the hands and debris out of your eyes.
Remove the spark plug from your mower so that the engine can't start while you are working underneath the mower. Also remove any fuel and oil from the mower to prevent spillage.
Tilt the lawn mower so that the carburetor is above the gasoline tank. This will prevent any excess gasoline you could not remove from the tank from contaminating the carburetor. Many fuel tanks and oil pans have drain plugs on their undersides, or you can use an old kitchen baster to siphon most of the liquids out.
Tip the mower on its side and secure it so that it will not fall or move while you are working with it. Also, place a piece of wood inside the deck of the mower to keep the blade from moving while you are trying to unscrew the blade.
Remove the mower blade bolt using a small crescent wrench. Squirt the bolt with penetrating oil and let the oil seep in before you try to remove it. It may take a good amount of effort to get it loose, so be careful that the wrench does not come off the bolt, causing you to skin your hands. Use a rubber mallet against the wrench to get the bolt started if you need to, or slide an appropriately sized pipe over the wrench handle to get extra leverage.
Continue turning the bolt until it comes off the mower and remove your blade.