So you want to know how to get out of a commitment? You start by facing the fact that you are not someone people can count on. Then you slink into your dance group and announce you are quitting because you do not have what it takes to be there.
Listen. I understand being uncomfortable, and being afraid, but life has many moments like that. You need to just face your fears and go for it. It is much better than living with t he regret of not even trying.