Two thoughts come to mind - one simple but it won't be exact and one more complicated but first let me warn you, I'm just learning advanced techniques in SW.
Simple, make a plane at the same angle as the "chamfer" and do an extrude cut to remove the material. The problem will be that the curves at the transition points won't be there.
The more complicated method would be to draw the curve on the back plane the shape you want and use a split line to project the curve on the vertical plane of the heel. Now loft to cut away what you're looking for.
Part of me is saying that there must be an easier way though. I saw as video the other day of the replace face feature and that very well could be the trick but I don't know enough to adivise on how to use it. Perhaps someone more skilled will chime in.