Thanks for the links. Sorry for not being that much clear. Let me clarify what I am trying to do. I have configured an Exchange mail account in MAIL client and recently I got a proxy password change hassle that I have to go through with that account. This scenario was repeated at least 8 times over the past year. The problem is I need to sync an empty address book to my iPhone to delete all the contacts on my iPhones and re-enter a more accurate list that I will upload from another imap gmail account. I know it may sound unclear still but thanks for your time anyway.
Now, for the purpose of testing, I created a group called "test" and from the "Edit" tab I scroll down to "Delete Group" and delete it successfully. However, deleting the group or the entries of the group related to that Exchange email account cannot be done for there is no such an option highlighted for an active click.
Sure I tried the backspace and delete keys as well as the fn+delete which works mysteriously in some cases e.g. on remote consoles.
Thanks again for your time