How quickly does one feel the effects of going off wellbutrin (bupropion) suddenly after having taken it for a few years?

As above: It is not a good idea to stop any medication without discussing this with u prescriber. And if s/he wants u to d/c it they can tell u how to do it.

Differs in people: Even though discontinuation syndrome is rare with wellbutrin (bupropion) there are reports of abrupt withdrawal causing dystonia, irritability, aches and pains and rarely mania. You should see it within a week.