Try opening a command prompt and deleting the files using DOS commands. You can try deleting them using the short version of the name.
For example, if the “visible” name is “Thisisaveryveryverylongfilename.mp3”, the short version of the name will likely be thisis~1.mp3.
You will therefore run the following command: DEL THISIS~1.MP3
with Windows 10 running in a remote session on my file server