Position the flathead screwdriver on the tab of the pal-nut in the center of the wheel.

Position the rubber mallet on top of the flathead screwdriver.

Hit the flathead screwdriver with the rubber mallet a couple times for each tab.

There are two tabs on each pal-nut, so just do these actions for the pal-nut on one side. The other wheel can remain connected to the axle to remove.

This is to push the tab inside to free the pal-nut from the axle that the wheel is connected to.