HELP!!! Broke Rocker Bolt

Broke a bolt to hold down one of my factory style rocker arms kit is almost up to the level of the pedistal i was trying to adjust after a rebuild and it was already cracked then i broke it trying to loosen it.

I need ideas on how to get the broken part out of the head without having to remove it again.

Someone already suggested a drill-out but that alot of metal shavings and how will i retap the head with it still installed and in the car?

no the bolt that goes through the rocker arm and fulcrum that holds it down to the pedistal