The Manage Users page is broken into sections
The "User Invitations" section shows any pending invitations you have sent out to a user.
They stay in the list until the invite is accepted, rejected, cancelled or expired.
The "User Requests" section shows requests from existing MyClub users to join your club. These are less common, in most cases you will have added and invited the user, so they will appear in the first section.
You need to review and either approve or reject these.
The "Current Users" section shows all the current (active) users in your club.
There are three categories of user:
The "Sandbox Users" section shows all the users who are in the process of being created.
The "Former Users" section shows all those who were once a user in your club.
Some data may have been retained , but what is available will depend on that status of the user's account. If the user no longer exists it will show as "Unknown User"