If you deactivate a member’s account, you have the ability to reactivate it. Reactivating a user's account allows them back into the platform and any Groups they were still an active member in.
Open Org Admin Page
To reactivate a Member from your Organization, select the Organization Administration icon from the top of the page.
Show Deactivated Members
To only show deactivated users, select the Deactivated checkbox . Deselect the Active and Pending checkboxes if they are selected .