I don't think there's any easy way to just quit. The first time, after 9 years, I was moving and gave 2-4 weeks notice I think (it was back in 1987 so a bit hard to remember :-) and that only messed me up for about the next 2-3 years, LOL. I saw the same therapist later, for another 9 years and we knew we were both going to retire and planned it, had a year and a half to work on it.

There's a big difference between quitting and terminating. The more you can do it together the better it is for each party I think.