Yep, I replaced the casters on my SM066 with larger ones pretty quickly. You just need to make sure the caster threads match. I seem to recall 5/16 - 18 thread size, but you can search here for the threads about it. I gently laid my smoke back side down on a pad and replaced them easily.
If you are wanting to just remove them to put the smoker on a cart, they can be unscrewed easily, but check to see if you still have room for the drip pan and a way to remove it.