Cannot get rid of files_external_onedrive

I have an annoying error with one of the users. They had previously installed the files_external_onedrive app, which worked for a period. Then it stopped working after a Nextcloud update, most likely because it didn’t have an updated version. After this the app was no apparently no longer maintained, and the user uninstalled the app. The folder for it however still shows in their folder list and in their settings page for external storage the share is still listed as external storage, with an error saying the reference to files_external_onedrive is unknown (which is obvious, as the app had been uninstalled).
I have looked everywhere in settings, as well as in the database, but sofar have been unable to fix this. Does anyone know how I can get rid of both the entry in the folder list and the entry in the external storages page for this user?

I’ve tried deleting the directory on the command line, but this results in “input/output failures”. It seems in config.php the entry for files_external_onedrive was removed, but I’m not at all sure I sure re-enter it and how:

'app_install_overwrite' => 
  array (
    0 => 'mail',
    1 => 'joplin',
    2 => 'keeweb',
    3 => 'calendar',
    4 => 'groupfolders',
    5 => 'audioplayer',
    6 => 'ransomware_protection',
    7 => 'spreed',
    8 => 'apporder',

It’s not really a show-stopper as NC functions like a breeze, it’s just a bit annoying.