Best way to release a pet is to set it on stay and run away with speed song. If you can’t do that, wait for charm to drop and stun+mez it, then run away with speed song.
Since your charm is instant, if your pet turns on you spam the charm button until it sticks. If youre fighting mobs, as long as your pet had solid agro before charm dropped, he should be able to get aggro back within the duration of a stun (cause you should stun the mob that now has aggroed you after your charm dropped).
There’s no easy way to learn how to control a minstrel pet on paper. It takes a lot of practice and you’ll probably die a lot. Just the way she goes.