Administrators and moderators can manage indidual users from Settings > Manage Users > Users. This page shows all users in your database including local, federated, and deleted users. You can filter/search for indivual users, and by clicking on their username you will see the management page for an individual user. From here you may:
From Settings > Manage Users > Invites you can see all invite requests and invite codes.
Invite Requests are requests from potential users who would like to join. These requests can be made when Allow invite requests is ticked in Admin > Instance settings > Registration. From the Invite Requests tab you can choose to Send invite to allow the user to join, or Ignore if you do not want to allow them to join your instance.
From the Invites tab you can create invite links to send or publish. You can set an expiry date, and a maximum number of uses for each link.
From the Force Password Reset page you can force a password reset for any group of users by category (user, editor, moderator, etc) or for all users. This may be required, for example, if you believe you may have had a security incident potentially compromising user passwords.
Note that if you select "All users", you will also be logged out and required to reset your password.