Come on, guys. You gotta know what's attached and what's structural. You've pushed out an old window or door before, right? Same thing.
I had prepped that bay, It was just setting in there, but tight as can be. But how is one guy gonna push a 9' bay window frame out? That sucker was heavy. You don't just jerk it all at once. You pull, very, very gently on this spot and that spot, watching to see how it moves.
Ah, an HST on the tractor is highly recommended!!
I've installed bay windows before, (along with 5 other guys helping hoist) but this was my first demo. It went very, very well.
It's really no different than pushing out a little 3x4 double hung, only on a much larger scale.