Re sacking someone - thats easy enough to do but - you really need them in front of you to tell them and give them their termination letter, ideally with HR alongside, the reasons -
a. Because you cannot let them carry on working or onto any aircraft,
as they could cause dissent or physical damage.
b. You need to get back the uniform and all ID's/passes they may have,
including car and specifically any airside pass.
The problem is going to be getting them in front of you, with uniform, passes etc., although I guess if the lure is the termination cheque to be signed for - which is only given on completion of handover - it might work.
Cheers
