There are some things you can change, and some things you could ask your GM/group to change. Adjusting the way your character is built might not be possible - that's not something Cyberpunk is good at, and I assume you want a crazy-good brawler anyway, so crippling the character is counterproductive. Maybe one of these would help...
1) Play him differently. It sounds like you're an unstoppable melee machine - so branch out. Start charging machine gun emplacements, assuming you can outrun the bullets and then kill the gun crews barehanded. Take on a tank; if you can force your way inside, they're in a lot of trouble. Or perhaps it's time to try knife-fighting or swordsmanship for a while, as a change of pace.
2) Find tougher foes. You're fighting zombies, right? A lot of martial arts moves won't be effective against the nerveless bloodless organless undead. Maybe your GM can introduce tougher zombies, or enemy soldiers in primitive powered armor that's too thick to punch through, or irritable Canadian mercenaries with ridiculous healing powers, or an enemy operative who's got the same stats/skills as you, or anything else that can't be killed with one punch.
3) Rebuild the other PCs. If the rest of the group just died, maybe their new characters should all be more like yours - hyperspecialized in something. It doesn't have to be handfighting, but if everyone in the group was insanely skilled at one useful thing, that could free up the GM to hit y'all with more unbalanced challenges.
4) Make a different PC. Maybe your current one goes missing, and his not-quite-as-trained little brother comes looking for him. That way you still get a specialist, but you have some room to grow.
5) Call your shots. Go for more specific hit locations, try for more outrageous success results, and just generally give yourself a higher target number in return for more interesting combat effects.
6) Tell the GM it's too easy. If you haven't talked to your friend about this, he/she might assume that you're having a great time being Sergeant Unstoppable Punching Man. Work together on creating better challenges for yourself.