Since Capricorn is the sign of order and stability, the key to getting a Capricorn either to leave you or for you to get out of the relationship, is to create a sense of discord, a sense of disorder or chaos.
Now this can be done emotionally, it could be physically; it could be just being plan messy. But in general for the Capricorn to feel that life is not in his or her control, gives a great sense of unease.
A Capricorn also wants to feel that the stability, the emotional stability, is there and therefore you can be counted on.
Again, by being a little mean, by criticizing, by not taking Capricorn's orders which Capricorn will never say are orders, but suggestions, by not paying attention to your work, by being sloppy also in caring about something, caring about doing a good job, caring about your family.
In other words, paying attention to your family responsibilities, all of this will quickly, quickly disengage a Capricorn.
A Capricorn, once he or she leaves, is for good. Just the way Capricorn went into the relationship for good, a Capricorn will also leave the relationship for good.
Very much like certain other signs that are controlling, Capricorn among them, it isn't wise to get into a physical confrontation because Capricorn, although does not show his or her temper often, does have a temper and therefore, you don't want to get into a fight having to do with words or even a physical fight.
In general, I would say that it's fairly easy to disengage from a Capricorn by not following and believing and adhering to what Capricorn values and that is good work, hard work, saving your money, being stable and being committed.