The only users who can see your data is coaches in your teams and coaches you have approved. Your data is not visible to any athlete.  

You can see and change who can access your data in "Manage access". Click on your name to the top left and then on "Manage access".

a. You can leave a team if no longer want to share your data with the coaches in that team.

b. You can remove individual coaches you approved earlier if you no longer want to share data with that coach.