How do I get the chain brake mechanism off my Stihl 029?

I want to take the crankshaft out of my Stihl 029 chainsaw, but the chain brake mechanism is fastened to it through the casing. How can I remove the chain brake assembly? I have removed the drum but the unit is still held in, there is a 19mm sized hexagon sticking out through the brake shoes, is this the securing device? please help.

Thank you.