The bracelet may actually still be on, but it is not functioning.
I do not think computer chips and other electronic technical do not work well after getting hit with a sledge hammer ( /saracam off).
Of course, hitting your foot with a sledge hammer might make your foot not function very well...
The person may not have removed it so much as disabled how it functions...
You can cut an ankle bracelet with a knife but it sends a signal when you do. So if on the run , you cut it off and run like hell so they can’t find you.
I don't know why. He was, after all, a criminal to begin with. They are pretty good at things like that.
I bet you could figure a way to defeat or remove the collar, if you had nothing to do but stay in your house all day with that darn collar on your ankle. Focus is a powerful tool.