How to Remove a User from a OneDrive or SharePoint Site

This will completely remove a user from the site’s UserInfo list which removes the user from any SharePoint group in the site, ACLs and even the site collection administrators group.  Sometimes this needs to be done for users that have left the university and then come back with the same NetID.  

A user or guest may appear in people searches and in the SharePoint Online Management Shell when you use the Get-SPOUser cmdlet. To completely remove people from the SharePoint site, you must remove them from the UserInfo list.

Browse to the site collection that the user or guest visited, and then follow these steps:

Note

This option is available only if the user previously browsed to the site collection. They won't be listed if they were granted access but never visited the site.

1. Browse to the site and edit the URL by adding the following string to the end of it: /_layouts/15/people.aspx?MembershipGroupId=0

For example, the full URL will resemble the following for a SharePoint site: https://nuwildcat.sharepoint.com/Sites/test/_layouts/15/people.aspx/membershipGroupId=0

For example, the full URL will resemble the following for a OneDrive site:  https://nuwildcat-my.sharepoint.com/personal/gjb865_ads_northwestern_edu/_layouts/15/people.aspx?MembershipGroupId=0

2. Select the person from the list, and then on the Actions menu, select Delete Users from Site Collection.

3. Go to Site Settings ==> Site Permissions

4. Click on Check Permissions and search for the user.  If the user is a member of a distribution list or some other AD group that has access to the site they user will have to be removed from the group or the group removed from the sites.

Microsoft Link è Remove users from SharePoint - SharePoint in Microsoft 365 | Microsoft Learn