you can download lxmed from here
instructions can be found here
Main menu editor can be found under preferences.
If you look at the menu, the items in dark green are those that are shown on the menu, the light green are hidden. If you try and delete an item you get told you can hide items.
If you select No go to properties you get this dialogue
If you uncheck visible the item is no longer shown on the menu, but is still available if you want to re-show it at a later time,.