Admin deleting users.

[ghost]

This is probably outside the scope of the project but it might be a good feature to allow the admin to delete accounts. This should delete the account both from firebase authentication as well as from the accounts database in the firebase database. This might have some implications such as:

• Logging out the user that was deleted if they are signed in at the time their account was deleted.
• We probably don't want the admin to delete their own account (could either exclude it from the user list or handle it separately after clicking).
  Note that deleting must be handled after a *long press.

We coulld ask the project owner if they want this feature or not.