A trustee in a trust deed may release the lien of such trust deed:
(a) When the trust deed authorizes the trustee to release the same;
(b) When the trust deed creates a lien to secure debts to persons not named in the trust deed;
(c) When a trust deed creates a lien to secure more than five creditors, even though such creditors be named in the trust deed;
(d) When a trust deed creates a lien to secure notes or bonds or other instruments payable to bearer.
A release executed by the trustee in any of the cases mentioned herein, and properly recorded, shall, as to purchasers for value without notice, be valid and binding, whether the debt secured by such lien had in fact been paid or discharged or not.