can you see the files you want to remove?
Are you logged in with the same Adobe ID that you used when publishing online the files?
If yes, sorry, I have no idea what's going wrong.
Maybe it will help to log out of your Creative Cloud desktop app and to log in again after a restart of the computer.
Maybe it would help to change the browser…
The »DELETE« works in MS Edge it doesn't work in Chrome.
This seems to be browser related issue. Do you have any extension for chrome that can be conflicting? You can also try to reinstall Chrome and check.
I found out the problem. Anti-adblock was preventing the website from pop-up delete verification.