Ok, I’ve found the solution.
I’m sorry, I’m not very familiar with the Linux terminal. The files weren’t listed (using command “ls data”), but they were there yet. I thought that using the command (“rm enable-usb-multi-gadget” and the same for the other two files) from inside the /data folder would work :-p
I had my suspicions, so I used the “find” command, and it showed me the files.
Finally, it worked when I used the full path with the “rm” command:
rm /data/enable-usb-multi-gadget
rm /data/enable-usb-audio-gadget
rm /data/enable-usb-windows-compat
Thanks for your help!