Select a “page” node in the binder.
Select “move to trash”.
The node disappears from the binder but the page is still displayed in the edit window and can still be edited.
When you delete an item in Scrivener, it’s just moved to the Trash folder in the binder (its icon is also grayed out to indicate it’s in the trash). It’s not deleted from the project until you empty the trash–this way if you accidentally delete something, you’re able to easily return it to where it belongs; you can also search for items in the trash, etc. the same as you can search the rest of your binder and load them in the editor to check the contents before you delete them for good. So all that to say, this isn’t a bug but the intended behavior.