Here is a quick demo of me trimming a cup or yunomi. First I tap to center, then trim.

A quick note about tapping to center: this version of centering on the wheel for trimming is extremely fast and I highly recommend learning it. For practice, use a coffee tin with some clay in it to weigh it down, or something of the sort. Otherwise you will have many ruined pots trying to learn this technique. But once you got it down, you can center anything (besides a wetter platter or plate) this way and it is super fast and effective. Go for it!!!