The short answer is I don't. I bottle it up until I'm afraid that if I express even a small sliver of it I'll explode and then I go some place and hide. While hiding I cry and scream and do whatever works until the level of frustration drops below the point where I worry I'll hurt someone.
Adam tried to point out to me that, at least in BJJ, I really ought to try to convert this anger into some kind of energy to apply to my technique. My problem is that when I get frustrated in BJJ, say, for example, because I've escaped from mount just to find myself in side-control (and on and on), my first thought is not "well, I'll just escape from this too, and this time I'll get on top". That might be productive. No... my frustrated thoughts tend to wander towards breaking fingers, biting, and poking eyes. Civilized people just don't do this, ok, maybe in the mythical "street fight" but never to one's training partner. So now I'm in the awkward position of trying to fight against one person to get out of side-control and fighting against myself to get my thoughts back to proper jiujitsu.
On top of this, I really don't think people perceive my reactions to being frustrated correctly. People seem to tell me things like "It's ok, everyone starts out a little claustrophobic." or "You'll figure out how to position yourself so you know you won't get hurt." Maybe I'm wrong; maybe I am dealing with a secret fear of being crushed. I think what actually scares me is how desperate I am in that moment to inflict as much pain as possible. It probably doesn't matter - either way I need to deal with it and get past it. I just feel like the advice for dealing with claustrophobia is "just breathe and realize you're safe" and breathing, though helpful, does not diminish my desire to destroy fragile appendages.
This is not just feelings either. When I get this frustrated and angry I will self-destruct rather than hurt another person. If my lip is bleeding, odds are its because I bit it until it did.
Don't think I limit my bizarre overreactions to BJJ. Other parts of my life are more frustrating than jiujitsu ever is. I miss my bird. I can't seem to get pregnant. I have motivation problems. Normal jobs bore me to tears. I take my frustrated rage and I hit the gym until I'm too tired to think about it anymore.
As far as jiujitsu goes, I'm trying two things. First, I need a better handle on what frustrates me. The worst, I think, is being caught in one position too long. Second, I'm starting to deal with frustration by not letting it get to the sadistic stage. Say I am caught in one position too long. I'm trying to count roughly to 10 as I am trying to escape. If I haven't managed to escape and my training partner is, for whatever reason, just not moving, I'll just tap out anyway. I need to protect my mental stability as much as my neck, arms, whatever.
If anyone has some better ideas, please, let me know.