I reactivated a user after two years but it had her old email address. Since she didn't remember her password from two years ago, we tried forget password but she never received the email. I realized...
The easiest way to do this is to put in a support case and get in touch with our Care Team. They can then help you to locate that User who is unregistered and invalidate it to free up the email address. You would do this by clicking on the Help question mark in the upper right hand corner while signed into Quick Base and then selecting manage support cases. You would just want to make sure to include the current user email you are trying to update and the user email address you are trying to free up to help the Care Rep locate and identify the user accounts.