Stopping mirtazapine without tapering

I have been to see my psychiatrist today and he wants me to stop the 15mg of mirtazapine that I'm on without tapering. Just finishing fini stoppped abruptly no withdrawal period. This is extremely puzzling for me because last time he had me withdraw by tapering ie withdrawing gradually. I experienced horrendous withdrawals and went back on 30mg. He also told me that 15mg was not a therapeutic dose. Puzzling as I was put on it last year as an add on to boost meds that I was already on. So who is he kidding? I trust this man with my life (absolutely) but I can do this in my own time no pressure. Has anybody done this ie stopped mirtazapine without tapering stone dead with or without side effects. I'm really confused. No doubt he will deal with the fall out?