How do you remove a bluetooth mouse? I have crosstalk between iMac mice...

Dear Pals,

My lab has a couple iMacs shoulder to shoulder. My helpful and friedly students paired both iMacs with both magic mice and now there is war betwixt them. Even when a mouose is disconnected, it will spontaneously reconnect if the other mouse drops temporarily (altogethr way to common, I'm afraid). I would like to remove one mouse from each iMac's bluetooth device list but am stymied. Can one of you show my the secret handshake?

Many thanks for our efforts, BF3