I installed a custom theme called StartupGrowth. At the moment, I am trying to edit the main navigation. When I go to Structure->Menus->Main Navigation and disable the unneeded entries, they do not disappear from the navigation. However, if I add a new entry to the menu, it does appear. What's more, when I attempt to delete the entry added by me, it persists in the navigation just like the other ones.
What am I missing? Is there another place for editing this menu? Or does this sound like a bug in the theme itself?