need to file a petition for decree releasing property from mechanics lien

If the lien is less than 90 days old, there isn't much you can do other than purchasing a mechanic's lien release bond. A release bond will immediately release the lien from the property. So this may be the most cost efficient approach to ensure that your refinancing is not interrupted. If the lien is more than 90 days old, you can send a letter to the contractor demanding that he release the expired lien per Civil Code Section 8482 within 10 days. You can find a model form letter if you google "demand to release mechanics lien CA." Send the letter via certified mail to the contractor's address found on the CSLB website. If the contractor still does not release the lien, you can file a petition to release the lien. At this point, it would make sense to hire an attorney, as the cost of the petition is recoverable against the contractor. But you can file the petition yourself. Just be careful to research all of the requirements for doing so and read through the Civil Code Section 8482 et seq statutes.