I have seen this multiple time.<p>I am now rewarding people and showing by example that you should find ways to make yourself redundant. Be able to go on vacation for 2 weeks while not receiving any calls, etc. The only person that is allowed to not be redundant is the owner of the company.<p>As to advice how to deal with the problem, it would very much depend on the history and combativeness of the employee. If the employee is very combative and a potential risk of doing something stupid, I would fire him immediately.<p>The benefit of this is you reduce a chance he will do something really stupid. You also show to the rest of the company what is and what is not tolerated.<p>If you have relatively good history and the employee is not combative and potential risk of doing something stupid, I would reassign another employee to get as much knowledge transferred. You want reassigned employee because it is already going to be hard following the guy even with the organisational knowledge. Ideally, you also want this person to be relatively high level, intelligent person that knows how to deal with ambiguity, manage problems, etc.<p>If he isn't cooperating, I would bar him from touching anything and force him to only work through the assigned employees in training under threat of immediate dismissal. So if he cooperates and works through those employees, he benefits in being in employment for longer, potentially having more chance to find replacement job.<p>Obviously, this will not solve the problem, it will only blunt the blow a bit. If that person had a long time to build his castle, it will be very difficult for the replacement to get the hang of it and a lot of knowledge is going to be lost forever. That's unfortunately unavoidable in this situation unless you really want to shower the person with gold to pass all that knowledge. But this is dangerous as it normalizes this type of behaviour and you really don't want your other employees' main takeaway from this to be that making themselves critical is the best way to get rewarded.