What I use now is a gear-puller…
But what I did before the gear puller was a little less elegant… Take everything off including the big nut holding the motor on… The motor is then pressed onto the axle at only at the center of the hanger.
Grab 2 sacrificial 8mm nuts, what I prefer is one standard nut on the inside and a nylock nut on the outside. tighten and lock the two nuts together at the end of the axle with the nylock hanging off, not engaged with the threads.
Grab a plastic dead-blow hammer… Use your big boy strong manly hands to grab the motor can firmly and progressively whack on the nuts on the end of the axle… what you want to happen is; the board is off the ground slightly, and by holding the can firmly you want to drive the axle downward and thru the motor releasing it from the axle…
Work up, slowly, to some manly whacks if you need to, but usually, a couple of firm whacks with the dead blow hammer will loosen the motor from the axle… whack once and check if it moves… what you want to avoid is everything coming loose at once… whack…check… if the can moved a bit… reduce the next whack… ease the can off the axle…
Usually, I hold the board perpendicular to the ground and whack down on the axle… the gravity of the board helps somewhat in over-coming the tight fit of the axle…
I’ve never damaged a motor or the axle threads removing a motor in this way and I’ve done it quite a few times…
I always had a bad feeling whacking on the motor can with a hammer… But yes, I’ve stood on an upside down board and gently whacked alternate sides of the back of the motor can with a plastic dead-blow hammer… I grimaced each time I did it… but I have friends that needed help…
remember when you’re doing all this whacking about… you’re an artisan not a blacksmith… but if the can won’t move… go medieval on it…
YMMV
and hope this helps…