Ubuntu – How to disable right click in nautilus

You can use Nautilus extension API for that. In particular I recommend Nautilus-Python.

Here's a simple example that adds a context menu item for MIME type text/plain:

from gi.repository import Nautilus, GObject

class ExampleMenuProvider(GObject.GObject, Nautilus.MenuProvider):
    def activate(self, menu, files):
        print 'activated' # do something

    def get_file_items(self, window, files):
        if len(files) != 1 or files[0].get_mime_type() != 'text/plain': return
        item = Nautilus.MenuItem(
            name='SimpleMenuExtension::Do_Something', label='Do Something')
        item.connect('activate', self.activate, files)
        return [item]

You'll need to install python-nautilus and gir1.2-gconf-2.0 packages and place the above Python script in ~/.local/share/nautilus-python/extensions/.

The "Create new document" dialog sources its entries from ~/Templates. Simply put an empty Libreoffice document in that folder or create a subfolder with multiple documents and you will be able to create LO documents from the context menu in Nautilus.

The same method applies to any other type of file, of course.