You're going to be asked about it on the application. If you lie, and it's later discovered you lose your RN license. They could fail to find it now, but computers somewhere could be upgraded in the future, or there's a more thorough background review at some point, or there's an investigation in connection with a medical malpractice suit where you work.... don't risk this. And don't risk having to live with knowing that it's "out there."
Especially if it's minor - disclose it. Hiding something / lying about it is generally considered much worse than the offense (for most offenses).
There was an attorney in NJ who failed to disclose a ten year old DUI. When they found out about it, he was disbarred for lying ... even though they probably wouldn't have made a bid deal out of it had he disclosed it initially.
IF YOU LIKE THIS ANSWER AND APPRECIATE THE TIME IT TOOK TO WRITE IT, PLEASE SELECT IT AS "BEST ANSWER." Thanks. The above is said without seeing your case file and without my understanding the entirety of the facts of your case. Depending on those facts, the above information be may incomplete or may be completely inaccurate. The above is intended as general information only based on what you described and not as legal advice. I advise you to consult with counsel who may be able to provide better information commensurate with a better understanding of your situation.
You absolutely need to contact a qualified license defense attorney in CO. Check The American Association of Nurse Attorneys ("TAANA") lawyer referral service for a list of reputable practitioners in that jurisdiction. Click here for the correct link: http://www.taana.org/referral .