If he is in violation of the lease then you can evct him and he will be responsdible for the remaining time on the lease. You have an obligation to try to rent it out as soon as possible but you can charge him for the expenses of trying to rent it out as part of your claim against him. If you own property that is in need of this type of service I suggest a good real estate attorney would be a valuable resource to have available when these issues come up, including knowing how to proceed quickly toward an eviction if needed. Sometimes people find that it is more trouble than its worth if the tenant does eventually pay each month, though late (with late charges tacked on if applicable under the lease)
You need to comply with Colorado's forcible entry and detainer statute. If you don't follow the proper procedures, the Court is likely to find in favor of the tenant at least for the time being and you will have wasted a lot of money and time. Failing to serve the proper notice and give the tenant the required time to pay the rent will prove fatal to your case. See link below and read carefully. If you don't understand the procedures or want assistance, consider retaining a landlord-tenant attorney in Littleton. http://www.courts.state.co.us/Forms/Forms_List.cfm?Form_Type_ID=28
This answer is for general informational purposes only and should not be interpreted as legal advice. Lawyers render professional legal advice based on the specific facts and circumstances of a Client's case. For legal counsel, contact me or another licensed attorney.
In order to evict a tenant who does not voluntarily vacate the premises, you need to seek the Court's assistance by filing an FED action; you can also seek damages (for unpaid rents, etc.) in Court. You have a duty to mitigate your loss of rent between evicting your old tenant and finding a new one, but generally the old tenant is on the hook for rent until the property is occupied. If you are unable or unwilling to retain an attorney to assist you, the Self Help section of the Colorado State Judicial website has most of the forms you need and some basic information to guide you in the process.
This response is for general purposes only and does not create an attorney-client relationship.