How to add draft along the red coloured edge which is marked in red of the below attachment?

This is not an easy task. Some questions:
1. what is the draft value you plan to add?
2. how do you like to draft, maintain each diameter at PL and make inner one smaller? OR , enlarge diameter at PL?

I suspect you may not be able to use revolve. But it depends.

See the attached file, is this something you want? Note that there is still no draft on the flat surface.

This has draft on the flat surfaces as well

Thank you, sir, for your response. I think I didn't clearly mention what I want, I'm attaching a file of what is in need but i couldn't control draft angle as i have just projected the sketch onto another plane and used blend option

can't really tell what you wanted to do from this file. You added 30 MM material surrounding the cavity and that creates more undercut on the cavity.

see this one.