Under "their contribution" there is a third party term option but I don't have access to it, it sais I can force them to leave alliance  or make them go to war or terminate an aggreement with a thrird party their involved in? Am I doing something wrong or this is still unavailable?

Resource term is anything from luxuries, strategics, while third party term can be technology, tribute (correct me if I'm wrong on that), and anything else, really, on the list that comes up. I think you simply misunderstood what "third party term" refers to.

Try it yourself, hover over third party term option and a tooltip comes up and explains that you can force them to leave alliance etc...

Interesting, I didn't notice that