Easy peasy:
- Go to 'Profile'
- Click 'Profile & account'
- Scroll down to 'Account'
- Click 'Deactivate or remove'
- Click on 'Remove' all the way down at the bottom
If you are only temporarily unavailable, but do want to babysit again later on, you can choose to temporarily deactivate your profile. You will then no longer be visible to parents, but your profile details will remain saved.