Have him fall in love and then dump him.

This energy master either interacts with the rest of the universe or he does not.

If he does not interact with the rest of the universe then he is incapable of being perceived, either directly or indirectly, and is essentially a figment of the imagination and need not be bothered with.

If he does interact with the rest of the universe then the interaction is mutual, meaning that there must be forces that can be directed at him which he cannot overcome. The best thing to do would be to annihilate him by the use of such forces.

Bonk them on the head.

I’m guessing something well padded and relatively small.

First you look for a single verifiable example of such an “expert”, and meanwhile assume any of the usual restraints sufficient until one can be “produced”. This is one of those questions along the lines of “Is it safe for my unicorn to graze with the rest of the livestock?”

@ragingloli is using this as a way to escape my room puzzles. So, I guess we can think of the best way to deny her ki hero escape…

Their are some Asian ornaments that are hung outside to prevent ghosts, or spirits, for entering or escaping. They where shown on the original “Charmed” series, where an Asian man is killed and has to find peace before his soul is captured by an evil death spirit.