In order to add users to a project, the users need to be added at the account level by an admin first. Here's how an admin can add new users at the account level:
Navigate to the Account level. Simply click the BUILDR in the top left corner.
Click Add User on the right hand side and enter their information.
Removing a user from Buildr is just as easy. Deactivating a user removes them from all projects (user can no longer sign into Buildr). If you wish to add or remove a user from just one project, that can be done in the project's Team section.
To Deactivate a User (completely remove them from Buildr):
Navigate to Team at the account level.
Click the trash icon next to the user you wish to remove.
Click Deactivate User at the bottom of the pop up window.