Once you have given the former tenant notice to take away his personal property, and here it seems to have been several months now, you are free to dispose of those items as you see fit.
See also Civil Code section 1965.
Frank W. Chen has been licensed to practice law in California since 1988. The information presented here is general in nature and is not intended, nor should be construed, as legal advice for a particular case. This posting does not create any attorney-client relationship with the author. For specific advice about your particular situation, consult with your own attorney.
You have probably held the property for a sufficient amount of time, however, emailing the former tenant may not have been proper notice.
Generally, there is no set time limit for removing a former tenant's abandoned property, just whatever is reasonable under the circumstances. But to protect yourself, you need to make sure you give the former tenant written notice that follows the legal requirements.
The Department of Consumer Affairs published a guide for landlords on how to deal with this situation. You can find it on the DCA website or go to this link for a copy: