Knickers
Warlord
Yes, as long as the ROP is in force, you'll take a rep hit if you DOW. Go into the diplo screen and pull up "Active Deals." Click on the deal that you want to renegotiate, then click it again and it should disappear from the box. That takes it off the table and you're free to DOW (assuming you don't have some other deal going which would cause a rep hit).
Edit: X-posted with Turner. Also, I didn't realize that you got a rep hit by canceling and DOWing on the same turn.
For the life of me, I can't find this place. Which diplo screen do I go to? Where do I find "Active deals"?? I'm playing PTW 1.27 (I think that's the right number, the lastest patch anyhow).