About the Admin and Guest accounts
Each database file initially contains two accounts: Admin and Guest.
Admin account
The Admin account is assigned the Full Access privilege set, which permits access to everything in a file. The Admin account is not assigned a password. In files for which privileges are not set up, the file options are set up to automatically log in to the file using the Admin account.
The Admin account is fully editable. You can rename it, assign it a password, make the account inactive, or even delete the Admin account. For more information, see Editing existing accounts.
Important  Don’t forget the account name and password that is assigned to the Full Access privilege set. If necessary, write it down and store it in a secure place. If you lose or forget this account name and password, you may not be able to access or change the file.
Guest account
You can permit users to open a file as a guest, which means they do not have to specify any account information. The Guest account determines the privileges for users who open a file as a guest. By default, the Guest account is assigned the Read-Only Access privilege set, but you can assign any privilege set you want to the Guest account.
Initially, the Guest account is inactive, which disables the guest option in the password dialog box and prohibits users from opening files as a guest. You can enable the Guest account to permit guest access.
The Guest account is not fully editable. You cannot delete the Guest account, change the Guest account name, or assign it a password. For more information on editing accounts, see Editing existing accounts.
For more information about opening files as a guest, see Opening files protected with passwords.