I rented a room to a person 8 months ago in California and initially he felt he would he would only be renting for 4-6 weeks. I agreed to cross out the "30 days" notice in the month to month tenancy agreement and substitute "15 days" notice. Shortly thereafter he verbally said he would be staying much longer with my agreement (verbal) and always paid on a 30-day cycle, on the first of the month. He recently stated he might need to move and I requested at least 30 days notice, which he agreed to. Now he has said he's moving within a few days and gave me a 15 day notice. Question, does the 30 day periodic rental payment superseed the 15 day notice in the rental agreement which was never formally changed?

The formal written agreement stands, a verbal agreement unless put into writing as a amendment will not over rule the written lease ( rental)