To add additional admin members to your site (with access to the site's Control Panel) and to prevent getting locked out of your own site, you can create extra admin accounts and should also create a second admin account for yourself. You would set your access level to the highest level and use it as a backup account in case you ever locked yourself out. You could then use the other account to unlock yourself.
Click on each section to expand for more information.
Under 'Members' choose 'Add New Member'
Enter in the Information for the Admin Member Account Including a Unique Username and Email Address
a. The Member Plan can be set to Plan 4 - Admin Account
b. No payment information needs to be input as the plan is free
c. Press the 'Add this Member' button
***NOTE: The username and the email address do have to be DIFFERENT than any other account
Click the 'Edit this Member' Button
Update the 'renewal date' and the 'Access Level'
Update the 'renewal date' to push out the date far into advance.
Update the Access Level.Please see this tutorial for descriptions of the access levels: Access Levels