Cannot Delete Folder that is Locked for some reason on Debian GNU Linux

Based on the setup of owncloud 9 described here
https://utopian.io/utopian-io/@h4ck3rm1k3st33m/installing-owncloud-on-debian-gnu-linux-sid

After we created a folder with a name in it, we cannot delete it. I dont know how it got "locked"

In the error message it misquotes the name with the url encoded char 39.
Error deleting file "Plans Ideas and ToDo's".

In the console I see a different message:
/owncloud/remote.php/webdav/Documents/ana/Experimental/Plans%20Ideas%20and%20ToDo's Failed to load resource: the server responded with a status of 423 (Locked)

Trying again gives this in the console

filelist.js?v=9f90720…:2401 DELETE http://debian-build-speed/owncloud/remote.php/webdav/Documents/ana/Experimental/Plans%20Ideas%20and%20ToDo's 423 (Locked)

Renaming the parent folder gives an internal server error

filelist.js?v=9f90720…:2055 MOVE http://debian-build-speed/owncloud/remote.php/webdav/Documents/ana/Experimental 500 (Internal Server Error)