I removed one of the hard caps tonight. Not only did I not destroy it, I didn't damage it one bit.
Used one of these...
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I straighten out the handle about half way. Put one of the hook ends in the cap's hole, then used it as a pry bar (with the bent tip pointing up) and the cap just popped off.
The key is to "pry". Don't just try to yank the cap out.
Funny you mentioned this, I was randomly looking for something to pop a top off the other day and used one of these! Works like a charm and usually gets both pieces out at once