Remove Link on menu item

Hi, I want to remove the URL link on my primary window and replace with # because I now only want it to display the submenu, not actually navigate to any page.
Problem is, there appears no way to change an existing link on a menu item. I know I could delete the menu item and recreate it, but I don’t want to have recreate my complicated Max Mega Menu from scratch (Max Mega Menus can’t be duplicated, for some reason).
Can anyone tell me where in the database I can change that link?
Thanks