You must mean how to pay your CA tax due--since a refund is money they give back to you. You can mail them a check or money order or pay on the CA tax website.
https://www.ftb.ca.gov/aboutFTB/contact.shtml
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
