Electric shutoff for non-payment how to get tenants to move out

[Ann Wood]

Rental property in Evans, CO.  Longtime tenants, husband was ill for several years before passing away a year and half ago.  Just found out via Xcel disconnecting electricity, that they had ran up a 'huge' utility bill (thousands of dollars).  Wife claims she doesn't owe it because utilities were in husbands name and she has only been paying $200 per month. Insane that this can happen.  Wife, children, and grandchildren are now in Denver because there is no heat or lights.  Rent was paid by Housing Authority.  Xcel will not put utilities in my name as landlord until house is vacated of all belongings.  Tenant told me today she has 30days from the end of the month to move things because Housing Authority said if they moved they needed to give 30day notice.  Non-payment of utilities is a violation of the lease.  Do I post the 3day Notice To Comply and mail via certified mail (which they will not get because they are not living there) and then file with the court for eviction?