Closed end Combination Wrench or Socket Wrench
Scrap piece of wood
Put on leather gloves and Safety glasses. Remove the spark plug wire. Turn your mower on its side with the fuel tank fill spout up. Lay a block of wood next to the blade and hold it firmly in place with your foot.
Fit the correct sized wrench on the blade bolt and remove the bolt, bracket, and blade. On most mowers turn counter clock wise to loosen and remove the bolt and washer holding the blade.
Now I’ve shown you how it’s your turn to “Git ‘er Done”
Phil The Gardener