What exactly do you mean by "page in a group"? Any screenshots?
If you navigate to the page that you would like to remove there should be a Delete button on the right side next to the Edit Page button. Special note its not the one in the Manage menu. Thats "the big delete".
Let me know if thats not the case and I'll see what I can find out for you. That should appear for you if you have the permissions to create a page (group administrator).