Just to add a comment to tie together the two answers below which both explain their part of the functionality well. You may know all this anyway, but in case someone else looks at your question later on hoping to solve a similar problem:
There are two different aspects going on here and I assume you want both parts.
- Calling 'delete' as you are (and as Sean de Wolski is explaining syntax for below) is done on a graphics handle(s) (or a handle-derived object in OOP) and will delete the graphics object. However it will leave the field still there on handles pointing to a deleted graphics object
- Using rmfield as Image Analyst shows below is the second part of that which will remove the field from handles that now points to a deleted graphics object.
Personally in the latter case I tend to just set the field to [] and test using isempty at other points in my code (having created the field in the GUI's OpeningFcn) rather than removing the field ans testing with isfield, but both methods are equally valid.
One advantage to using the [] option though is that you can call the equivalent of
delete( [] )
without a syntax error. However, what you can't do is call
delete( someGUIHandle )
if 'someGUIHandle' is neither empty nor a valid handle (i.e. you have deleted it as you do above) so you do usually still need to do the ishandle( someGUIHandle ) checks before calling delete to be sure.
