I think this cannot be done because there is no softkey called end meeting , this can only done by MeetingPlace Express which has some good features like "End Meeting". Please find the below link for more information:-
Unfortunately this is not possible with Meet-me, AD-hoc conferences on the other hand you can. If the conference initiator dials a meet-me number and then conferences the other parties instead of them dialling the meet-me number then the same behaviour would apply as they are AD-hoc. If you wish AD-hoc conferences to drop when the initiator leaves then set the 'Drop Ad Hoc Conference' CallManager service parameter under Feature - Conference to 'When Conference Controller Leaves'.