Paul
I understand your question - you are specifically asking whether delete functionality should be built into your GUI. I would say that you should not expect to drop points for omitting this, since it is not required according to your instructions. My instructions only require the GUI to allow search and book, not delete or create, so I will not be adding that functionality to the GUI.
However, this fits into the broader question of whether or not all of the methods of the data access class should be available client-side (whether or not you provide GUI access to them). For example, if you do decide to add delete functionality to your GUI, your server will obviously need to expose the corresponding method. This then begs the question 'Do I need to expose all of the db functionality to the client, even though the specific GUI requirements are much more limited than the db?'.
So, even if you decide not to provide that functionality on your GUI, you may still want to think about whether or not it is available to the client. It all pretty much hinges on your interpretation of the
word 'provide', as discussed in the thread above. If you do make it available to the client (which I will not be doing), it does make it easier for you to add it to the GUI later if you feel the need.