Your iHealth tracker is intended for your personal use only and is linked to your iHealth account. If you want to lend or give your tracker to a family member or friend, you must first reset it to restore the original configuration.
To leave the account linked to the tracker:
MENU > Set up my devices > AM3 > Reset.
This Reset erases all your personal data from the tracker, including unsynchronised data. So be sure to synchronise your data with your iHealth account before this Reset.
You will not lose previously synchronised data.