Contact the owner of the SharePoint Online site where the shared file or document is stored to do the following:
1.Open the SharePoint Online site where the shared files are stored> Settings> Site Permissions> Advanced Permission Settings.
2.Open the Site Name – Members Group> In the end of the URL, change 5 to 0> Click Enter.
3.In the People and Groups page, select your name> Site Actions> Delete this user from the site collection.
If still the same issue, please access the shared files in the InPrivate or Incognito window and check whether you are able to access.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.