[Viking2002]

A good, old-fashioned bulk eraser, just like DJ's used to use in radio stations. Zap it with EM for a few seconds. It'll depolarize the whole thing and render it inert.

[unkus]

Where can a bulk eraser be found?
After the deed is done, it would be best just to plead ignorant.

[sionnsar]

I don't think this is at all the same technology as is used in anti-theft tags (which, you are correct, could be rendered inert this way).

The RFID tags I've seen from 1990 on generally store energy from a received RF burst and emit an RF signal, typically conveying a fixed unique N-bit code. A microwave oven *might* damage these; a mini-EMP generator could also (I am guessing).