Back the tractor up to the tree with the rotary mower in the up position. The mower should line up with the tree.
Engaging the PTO drive shaft makes the mower blades turn. Depending on the tractor, the PTO drive shaft may start the blade whenever the tractor drives forward or backward, making this step unnecessary.
Lower the mower deck onto the tree. This is done with either a hand lever or a turning knob, depending on the tractor make and model. Prepare for a loud noise as the blades shred the tree.
Raise the mower deck when you can no longer hear the tree under the blades and check the cut’s progress. The mower should mulch the tree completely with just one pass, but another pass may be required.
Approach the tree from another angle and lower the deck. Continue cutting until the tree is completely gone.