How delete Locked files without line command?

A file is localy deleted but not on the server and I’ve always a synk error message.
It’s impossible to delete it on the web interface
I tried to dowload it from the web interface to my desktop an delete: error message again.
There are many post about this kind of error and solution with command line
I don’t have any acces to command lines. Only the web interface
Any idea ?

(13.0.11)