Would suggest you talk to him and explain the criticality of the responicibilities.
First talk to his manager and understand how critical is this resource , howmuch time it takes to do the KT .
Get a new replacement for this job( if you get any body internally.) ask the employee to hand over all his responcibilities.after conformation of the manager and the new replacement on proper KT you can release him.
for that at least he should spend 7-14 days(including week ends)
If this does not work out you can go ahead as our frnds suggested above
First talk to his manager and understand how critical is this resource , howmuch time it takes to do the KT .
Get a new replacement for this job( if you get any body internally.) ask the employee to hand over all his responcibilities.after conformation of the manager and the new replacement on proper KT you can release him.
for that at least he should spend 7-14 days(including week ends)
If this does not work out you can go ahead as our frnds suggested above