Until now, WordPress user accounts are either on, or non-existent. There’s been no option to suspend user account such that they’re still on your site, but login isn’t permitted.
Shield helps admins to suspend a user and prevent any further login. It doesn’t delete the user, or affect their posts or change any other aspect of the account. It simply prevent authentication by that user and thereby no login is possible.
Only the admin may unsuspend these accounts.
How to manually suspend WordPress user
To do this, you'll need to go to User Management module of the Shield plugin => User Suspension => and enable "Allow Manual User Suspension" option first:
Then, you may go to the profile page of the user you want to suspend => check the "Suspend Account" checkbox => and click to save:
The user account that is “suspended” will never be able to log into the site (until they’re unsuspended).
Note: To unsuspend the user, just uncheck the "Suspend Account" checkbox (see the screenshot above).
When a suspended user tries to login, they’ll be told the account is suspended and they’ll be directed to contact the site administrator:
To learn what to do about inactive WordPress accounts, read the blog article here.