I am an employer. I have 1099-Misc. State is CO Do I have to submit Copy 1 to C0/ If so, what address?

You only have to file forms 1099-MISC with the Colorado Department of Revenue only if they contain Colorado state withholding information (when Colorado tax is withheld and reported on the forms).

Please read this document:

https://www.colorado.gov/pacific/sites/default/files/Income2.pdf

If you have to file, the address is: