Pages are not deleted from menus
It looks like pages are not deleted in menus when you delete a page itself.
1. Create a new page
2. Add it to the main menu
3. Delete a page
Clear cache - no result so far. It's still in the menu.
1. Create page - demo
2. Create plugin that adds extra page - demo
3. Delete page demo / Install plugin
You can see the page in the menu.