Removing these links is easy, and has been answered here.
Among the many answers there, the cleanest approach may be to
- delete each entry in .config/user-dirs.dirs. Better yet, comment each line out - place a
# before each line. This way, you can restore the previous state easily if you change your mind.
- Make the change persistent by disabling an automatic update of this file: create a file .config/user-dirs.conf and add a line
enabled=false. You can actually do this in a very quick way with a single command:
echo "enabled=false" > ~/.config/user-dirs.conf
Alternatively, set each entry to "$HOME" to have the bookmarks disappear.
I did not succeed in adding custom links to these "special folders". However, for practical purposes, regular bookmarks, that appear in the section below the special folders, work equally well. For example, to add a bookmark to
/opt/lampp/htdocs, navigate to that folder and press Ctrl+d to add the folder as a bookmark. It immediately appears in the left pane in the bookmark section. Right-click the bookmark and select Remove to remove it again.