OCS-APIRequest: curl -u admin:secret -X DELETE ... always results in statuscode 101 (failure)

Hello,
this API command always results in statuscode 101 (failure)
curl -u admin:secret -X DELETEhttps://myserver-url/ocs/v1.php/cloud/users/UserNameToDelete’ -H ‘OCS-APIRequest: true’

while other commands are working fine like
curl -u admin:secret -X GEThttps://myserver-url/ocs/v1.php/cloud/users/username’ -H “OCS-APIRequest: true”
or
curl -u admin:secret -X PUThttps://myserver-url/ocs/v1.php/cloud/users/username/disable’ -H ‘OCS-APIRequest: true’

In the apache access.log I only see the try of the DELETE command without an error.
In error.log and nextcloud.log I see nothing.

I also tried a new apache module and activated something like this in a Location block:
AllowMethods GET HEAD POST PUT DELETE CONNECT OPTIONS

How can I activate or allow the DELETE http request which seems to be forbidden?
(latest nextcloud, apache2.4, ubuntu 20.04 LTS)

Thank you,
Rappi

In the gui it doesn’t work too!
After hours of try and error I found out that I have to remove the AD group (that allows nextcloud access) of the deactivated AD account.
So it is solved for me.