There is only one top-level admin for an account. This is the user account first created when you registered for a LibraryH3lp trial.
However it is possible to have as many administrators as you want for your account. Any user can be granted administrator privileges by adding them to the Administrators group in the Permissions and ACLs dashboard page (US, CA, EU, SG).
If you just want one admin account to have admin privileges and don't like the username of the current top-level admin, you can rename any user via the Users dashboard page (US, CA, EU, SG) by double-clicking on their entry in the Users list.