How do I get rid of this rust in the trunk?

Thanks guys I don't have a blaster and I definitely don't want to put any more of the POR15 down. I'm trying to get rid of it. The stuff is nasty.

I think I'm going to try some of that Evaporust and see what happens. My neighbor said he has some Ospho I can try but I'm kind of worried about the whole neutralizing it so I can safely paint over it deal. Was doing some reading and I guess Naval Jelly has the same chemicals so I guess I'd have to neutralize it anyway.