A very general rule of thumb is decreasing in reverse of the titration rate. Better yet, even more slowly. But definitely never coming off at a faster rate than you went on, as that can create some very serious problems.
I know a site that has some good info, but it covers a lot of ground. If you could remind me what you're on, I can try to find relevant specific pages so there's not so much to wade through.

(Not saying you should go off, but... it'd be totally hypocritical, as I've done it before myself, and I'd rather see you at least do it as safely as possible...)