How do I draft this portion of the part ?
Uploading your model could make answering easier.
It is not exactly clear what kind of draft you wish to add to that portion of the model, but how about using the split Line command to split your model faces. Then you could use the draft tool on a single face at a time?
You could also create a sketch perpendicular to the face you want to draft, and simply use a cut feature to remove the unwanted material.