Originally Posted by JTGraphics

Ok if were my frame I'd remove wheel and rear derailler as in your photo.
Lay the frame with that side up I'd get a solid heavy piece of steal or a large sledge hammer head old it on the bottom side tight up up to the hanger and take another hammer and tap on the bend it will flatten right up you must hold something solid against it same method a body and fender person would use to remove a dent, fast and simple.
Do not just grab it and pull it will bend in the wrong place and make it worse than it is and end up like a wave.