I would also love the answer to this. I went through every single tab under Advanced Settings but couldn't find anything related to this. I am not concerned about what family members ADD to the tree, but my fear is that someone could accidentally delete an entire photo album by mistake. I don't know whether the system confirms deletion. But I would just prefer it if certain things could only be deleted by the webmaster. I guess I will create a phony album, add a picture to it, and then see if it is easy to accidentally delete it.
I would also like to know the answer to this. It is a matter of keeping one database, without it having to be edited by all family members.... I'd rather be the webmaster that does the editing.