Most riding mowers cut with three blades turning under the mower deck. This deck must be removed to replace or remove the blades. All three of these blades can sustain damage and wear and tear from constant mowing. Generally, manufacturers recommend changing or sharpening the blade annually. Inspect the blades after each mowing session for rust, nips or damage and replace promptly.
Park the mower on a level surface. Engage the "Park" brake to ensure the mower is stationary. Remove the sparkplug wire from the sparkplug to ensure the mower cannot start accidentally.
Raise the deck control lever to the highest setting and place one wood block under the mower deck on each side. Unscrew the bolts holding the deck in place with a wrench. These are located beside the engine pulley. Remove the deck belt from the engine pulley and roll the deck from under the mower. Some models have deck hangers that fasten the deck to the mower. Remove if present by unlatching.
Turn the deck over to expose the blades. Unscrew the nut in the center of the blade, turning it counterclockwise with a wrench. Slide the blade off the spindle. Repeat the process with the remaining two blades.