mods.scd is an original file. Thats ok.
Look at the timestamp of all files.
Original files should have all the same timestamp (installation date)
All other .SCD with different timestamp can be deleted.
If you delete to much you can redownload it by checking game files over steam.
Simply uninstall and reinstall does not remove the mod files.
We still have to find those files and delete them.
And try to find the file or folder "GAZ_UI". its maybe a .scd or a ZIP file. Also search hidden folders on your HDD.
GAZ_UI is present, you just have to find it