It can be a bit tougher to leave when on staff than when just taking courses and whatnot.
But I think the same method could be used either way. I would say to just leave and take no calls from them. Don't talk to them about it. You'll end up being argued with, being sent to ethics, being "handled", being put on routing forms. I know, cuz I've experienced all that- as have many others here.
If it were me, and I had it to do all over again (I've left twice. Once when on staff- I "blew"- and once as a public) I would just stop coming in. If you have caller id, that can help with call screening. Screen your calls. Change your number if you have to. If you have cell and landline but they only have one of the numbers, screen the calls and mainly use the other line til you get your number changed, if you decide to do so.
They may send someone around to your home to talk to you. Tell them you have nothing to say. Look bored when you say it. Not angry, not thrilled, just bored. My husband has said in the past that one should "stonewall" when in those situations.
I honestly think that's the best approach, from what I've seen, from what others have described to me about their experiences and from my own experiences.
From "Office Space":
Joanna: You're just not gonna go?
Peter Gibbons: Yeah.
Joanna: Won't you get fired?
Peter Gibbons: I don't know, but I really don't like it, and, uh, I'm not gonna go.
Joanna: So you're gonna quit?
Peter Gibbons: Nuh-uh. Not really. Uh... I'm just gonna stop going.
Joanna: When did you decide all that?
Peter Gibbons: About an hour ago.
Joanna: Oh, really? About an hour ago... so you're gonna get another job?
Peter Gibbons: I don't think I'd like another job.
Joanna: Well, what are you going to do about money and bills and...
Peter Gibbons: You know, I've never really liked paying bills. I don't think I'm gonna do that, either.
Joanna: Well, so what do you wanna do?
Peter Gibbons: I wanna take you out to dinner, and then I wanna go back to my apartment and watch 'Kung Fu'. Do you ever watch 'Kung Fu'?
Joanna: I love 'Kung Fu'.
Peter Gibbons: Channel 39.
Joanna: Totally.
Peter Gibbons: You should come over and watch 'Kung Fu' tonight.
Joanna: Ok.
[Peter nods]
Joanna: Ok. Can we order lunch first?
[Peter nods again]
Joanna: Ok.
Just leave. Immediately. Staff or no, you really don't have any of the obligations you think you have to them at all. Don't worry about "freeloader debt" (doesn't really exist, and you don't care, you won't be back to beg anyway), don't route out, just go away from them and recover your life.