One of the most fundamental rights that a tenant cannot waive is the landlord's obligation to terminate tenancies through due process.

I want to have the capacity to terminate their lease if needed.Is that lease valid?

Terminate their lease for non-compliance.

At the same time, look to see if he left any contact information behind and reach out to family to determine his status.If you can't contact anyone soon, I would consider moving his belongings to storage, terminating the lease, and finding a new roommate.Because you are in California, I would consult an attorney.

Make sure it explicitly explains the process for termination if you are unhappy with their services, especially if they violate the terms of your agreement.3.

Don't terminate the lease or deal with their deposit until a replacement tenant is paying rent!

I had all new smoke detectors with 10 year batteries put in, so I wouldn't have to worry about changing dead batteries - that beeping can ruin a guest's vacation. 

My W2 employment will terminate at the end of 2024 so just trying to plan for the future if/when rates go down, how to best approach a refinance. 

Termination of a month-to-month tenancy is typically controlled by state statute.

Make sure it explicitly explains the process for termination if you are unhappy with their services, especially if they violate the terms of your agreement.3.