If you're an account owner and need to make one of your teammates and admin or you're a user and want to be an admin, getting that set up is simple.
The account owner or an existing admin just needs to head over to their team page.
There, select the ··· menu next to the team members name and choose Make admin.
And that's it. Any team member that's and admin can now add or remove other team members, as well as assign other team members as an admin.
To get started with making a user an admin, head over to your team page.