If you have good access to the foot and it's not set into a hole then get a
paint brush like this one. Start on one edge of the foot and gently brush lengthwise against the foot where it's attached. This will cause the nem to start to release after a little bit. As it releases keep working on it until it lets go. It may take a few minutes to get it loose but the nem will eventually let go on its own and no risk of damage at all.
This trick will also work if part of the foot is buried in a hole, but you'll need to also point a powerhead at it after the rest is loose to get it to let go the rest of the way.