Should I do handover of tools and methodologies I have developed? In some months my contract at a research university will end. 
During my employment I have developed tools and methodologies that are of interest to the research group.
At present, I am the only person in that group that has in-depth knowledge on several topics.
Nonetheless, my employment will likely not continue.
My priorities are to finish up research papers, so that I can apply elsewhere.
I expect to be asked to hand over the knowledge that I developed.

Now my question: To what extent should I cooperate?
One the one hand, cooperation seems like the decent thing to do. 
I am dependent on my employer's recommendations, and do not want to burn bridges. 

On the other hand, I would abolish my employer's need for me, which feels like self-sabotage. 

I have offered on several occasions in the past to hand over that knowledge and to collaborate.
Now, frankly, my highest priority is to get output, and not train somebody (or multiple people).
Yes, I'm afraid you do need to hand over all work product that you created while employed. You were part of a team and if you try to subvert the team by withholding things that arise from your employment on the team you are trying to blackmail them into keeping you employed. I smell a lawsuit here. 

But you should cooperate fully just as a way to boost your own future career. How do you want to be spoken of in this field? Do you hope that people will want to collaborate with you in the future? What value will your tools have if no one wants to come near you in the future. 

And without you or your contribution, the team will find someone who can provide an equivalent service. You may feel indispensable, but you are not. 

Sorry to be so harsh.