Didn't need a lot of force - just a firm push I seem to remember. When fitting, you hook the end of the link (which is bent over 90 degrees) over the clip and then push it until it locks. Removal is reverse of this, so you will need to push the link towards the actuator and then lift it up.
I was warned not to drop the link if it is a rear door as it will disappear into the bowels of the door never to be seen again.
That's another reason to take the window frame out - if you can get the 55 (I think) Torx on a small socket set, they come out quite easily, and everything becomes MUCH easier. Only tricky bit was detching the window from the window regulator, but the whole lots comes out in one go and you can see what you are doing.
Cheers!