The Admin tag is a system tag and gives a user Admin permissions; it acts differently to the user tags that you can create for Regular Users.
Click onto the user page and click on '+ Add a user'.
Add the individual's details and select the blue Admin system tag from the tags dropdown.
If you'd like the individual to be notified by email to complete their login, make sure to check your notification settings.
If you'd like to give an Admin tag to someone that is already on your user list, click the small chevron on the user's row and click on the 'edit user' button.
That's it! You can add up to 5 Admins for free and an unlimited number of Admins with The PRO Pack. Check in on the article in this section called Booking Admins for more information on Admin permissions.