What you are attempting to do is get post-conviction relief. Unfortunately this is very difficult to do so many years after you were convicted. You can contact an attorney to file this motion, called a 35(c), and see if the judge will help you. However, you will likely just spend a lot of money and not see much for it. Further, the attorney may not be able to find a legitimate legal excuse to file the motion so late. Thus, the motion might never be filed and you would owe the attorney for investigating your case. This being said, there may be a legitimate reason to file this motion and you will not know unless you get an attorney's opinion.
Unfortunately, Colorado does not allow sealing of any convictions, except for some possesion of drug charges at this point. If your plea of guilty was a part of a deferred judgment/sentence, you should be able to seal your record. If it was just a straight up plea, I am afraid you will have the conviction on your record.
Colorado does not allow for the sealing of convictions. Additionally, the time period has elapsed for any collateral attack on your conviction. I am sorry.
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Unless there was some defect in your plea, which you did not mention, or you were granted a deferred judgment and sentence, you will not be able to withdraw (recant) your plea and you will not be able to have it expunged. Sorry