Hello.
You'll be needing two flat bladed screwdrivers and a small hammer. You peck one of the screwdrivers between the lip of the wheel cover and the wheel itself, the peck the other screwdriver in between them about six inches around from the first, gently pry them both outward until the teeth of the wheel cover start to turn loose, move one of the screwdrivers around to the other side of the other screwdriver, again, about six inches apart, gently pry some more, and work your way around like that until the wheel cover pops loose. Just take your time and don't get too enthusiastic with it and you can get them off without damaging them. Hope that helps.
65 mustang wheel cover help 
