Rounded allen bolt - tips needed!

so another gimp move in bike maintenance by myself.
i've gone a fucked the allen key bolt (6mm) on my profile cranks - so it's essentially locked on the wheel.
any advice on getting this off?
i dunno if i can saw it off.. but willing to give anything a go to get this fucker off.

arent the profile allen key bolts sizes imperial?(american size and just a little bit bigger than 6mm) if so i suggest buying some park tools of the correct size so it doesnot happen again