In my game I have a NPK that has lost all his honor and is now acting like a bandit. He will the adversary in the coming year and I am wondering how to deal with it if he is captured. We are in the Anarchy phase and the PKs are the ruling body (they have formed a council and one as officer of the earl acts as the Chancellor another the Justiciar ) at the moment in Salsibury and I was wondering what they could do.

For instance:
Can they strip a man of his knighthood? The NPK was a vassal of Duke Gorlois and has no lord at the moment. But now he is acting like a bandit, and not in a knightly manner at all. So who can strip a man of his knighthood?

I know that in the Anarchy phase you can get away with a lot, so they could do it, but what would other knights think of this? Who would do this in 'normal' times?

Who can?

God.

Seriously - unless he joins the Church, he's considered a knight until the day he dies. A king could declare him an outlaw, but there is no king

In this specific case, there's little the PKs can do beyond put a price on his head - he isn't a vassal of Salisbury, so he's not acting in treason or anything like that, and there's no higher court for them to go to like there will be in later periods. Basically, in the Anarchy, if he walks like a bandit and talks like a bandit, he's a bandit - albeit one with better equipment, skills, and a higher glory reward for defeating than most.

EDIT: I found in the rulebook a punishment called degradation, which is an even worse punishment than outlawry and does, in fact, remove knighthood. However, from my reading, only the knight's liege-lord (who is dead) or higher (who don't exist) can perform this, so, no, your PKs can't perform this act on the NPK.

I don't think anyone needs to do this
0 honor = not a knight
certainly he does't care what anyone calls him

The county court is the body that usually declares someone to be an outlaw
A county court needs a sheriff
appoint a PK to b sheriff
declare that a trial was done (off stage) and outlaw him
then anyone can kill him on sight and not suffer any penalty

BTW, this sound like the kind of guy who might built his own castle nearby in the county
so much easier than capturing one!

-g