Create an account at Continental.
Create an account on points.com.
Wait for someone to post an acceptable ratio trade.
Trade them for Continental.
It is all about what people value their points they want to give away at. Granted, DL skypesos aren't really in demand, but I did find several 1 : 1s of CO : DL.
Send them to United.
It will cost you money (in trade fees), but it is one option if you are determined to shed your DL miles.