I had a similar problem. Just take it off and sit it in the sun. It might ripen up a little more. Having a little green on a pumpkin isn't bad. Sounds like my pumpkin has more green on it than yours does. After just a day in the sun off the vine I noticed less green already. They ripen up pretty quickly once they get started.

The photo I'm posted was taken yesterday after mine broke off the vine. It's actually more orange in person and the back side of it that you can't see in the photo is all orange with no green at all.

I found some info for you on how to ripen your pumpkin off the vine. It's pretty simple really.

Here is a link that might be useful: ripen your pumpkin

Mine hasn't started turning orange yet..

Should I just leave it in the patch so it can get sun?