Be sure to write clearly and sign/print your name exactly as spelled on the front of your title. Avoid white-out, scribbles, and strike-throughs.
Only one owner must sign if title states "OR" between owner names printed on the front of the title.
Both owners must sign if title states "AND" or "AND/OR" between owner names, or if nothing is listed between owner names.
If your Colorado title shows a lien or a bank name printed on the front, then your title will need to be signed off by the lien holder or have a separate lien release letter.
Colorado Department of Revenue DMV - Titles Section Denver CO 80217DMV Website