Good advice from Sports Girls Play:
It doesn’t matter what sport your child chooses, at some point she will come to you and say that she wants to quit. It’s perfectly normal!
Everyone has a bad day, everyone has a rough patch, and as a coach or a parent, it is your job to help your athlete get to the root of the problem, create a coping strategy, and get through the down time. …
… make a deal … stick with practice until the end of the month, after all, they have already paid for it. After each practice, the athlete needs to tell Mom one positive thing about the practice. At the end of the month, they will discuss whether it is time to try a new sport or to keep going.
I have a feeling that by the end of the month, all will be just fine. I have seen this situation play itself out hundreds of times over.
That post has more good tips on how to keep athletes in the sport.
My experience when an athlete summons up the courage to tell me they are thinking of quitting: stay calm, be very understanding and sympathetic.
The worst thing to do at that moment is to try to talk them out of it. Or to get emotional.
Simply set a last-training-day, quietly and confidentially, at least 2-weeks in the future.
In well over 90% of cases the athlete decides to stay on. Especially if the parents are supportive.
Often the kids are simply trying to communicate something difficult to verbalize. It’s easier to say “I want to quit” than to explain the more complicated issue to parents and coach.
Gymnastics Coaching.com 