If the need arises, it might be necessary to cancel an appointment that you have organised, which should automatically remove the appointment from everyone else's calendar simultaneously.
With the web client, it's not very obvious where this option is. There is certainly no option in the menu of the appointment, which I can find. There is however the option "Delete", when I right-click on the appointment listed in the calendar and this claims to allow me to remove the appointment. This took quite a long time to find.
For the sake of usability, I would strongly recommend you to replace the string "Delete" with "Cancel Meeting", making it clearer that this is what is intended and not the simple removal of a database record in your own calendar.
I would also ask for you to provide this an additional menu option adjacent to "Resend" and "Delegate" on the actual Groupwise appointment itself. It's the logical place where people would look for this function.