Yes. You can transfer access from one user to another by going to your AP Stylebook Online license in the "my products" (https://www.apstylebook.com/licenses) section and click the "manage my account users" link for the license:

On that page, you can add and remove users from your license as needed with the "Yes/No" radio buttons listed on the right for each user:

If you want to remove a user from your account entirely, you can do that via the "manage user" (https://www.apstylebook.com/account/account_members) by clicking "remove users" listed with that account.