If you are using Trisquel 7 and haven't gone out of your way to install a new
desktop environment you are almost certainly using GNOME. See Magic Banana's
comment.
It sounds like you have figured out how to manage the bottom panel.
As for the launch menu, does the editor look like the attached screenshot? If
so, you should be able to select an application group (internet, office,
etc.) and check/uncheck the applications you do/don't want to appear in the
launch menu. The launch menu should be updated even before you close the
editor, so try that and see if that works.
If that doesn't work, go to "Add/Remove Applications," install Menu Editor,
and try using that instead.
