This is how I take the hub/drum off a Exmark. Put the nut back on, just a few threads, you will understand later.
Put the puller back on....
If you have an impact gun, great.
If you don't, it'll be harder. Get a breaker bar and crank the puller down untill it is tight. Tap the drum with a hammer, crank down on the puller. 1/4, 1/2 turn, tap the drum with the hammer, repeat. Repeat untill the drum pops.
Tapping on the drum will set up a vibration in the hub.
If your wheel motor is typical, the hub is on a tapered shaft. The hub will pop off .