A friend used my computer, and sync is set up with HER email, and I would like to delete that and put in my email address.

I don't recall setting up sync acct. But am not computer savvy (can get by). Was checking out Sync and discovered that an acct is set up, but not with my email. My friend has used my computer, and I don't know if she meant to do it, but now acct. is under her email, and I would like to change this, but am afraid of deleting all data, and making a mess of something already messed up.