Exists a very easy means to be alerted when a LinkedIn link disconnects?
AFAIK there isn't a (indigenous) remedy to get alerted when a person separates from you on LinkedIn.
Nonetheless, I would certainly additionally assume it's unacceptable. It's like claiming:
I no more intend to talk with you! Kthxbye!
In addition, what usage does it have, if that individual proactively determined no more to be in contact with you, it's not likely you can transform his mind (or otherwise worth attempting)