How to remove Music from Ubuntu 14.04 file manager

I want to remove Music, Videos and Pictures from File Manager in ubuntu.

*i.imgur.com/dLUvGJb.jpg

I tried editing files

~/.config/user-dirs.dirs
~/.config/gtk-3.0/bookmarks

Click to expand...

changes to ~/.config/user-dirs.dirs get lost on reboot.

~/.config/gtk-3.0/bookmarks changes don't get reverted on reboot, but it look like not the correct file, it is only used for bookmark ?