Legal Question in Real Estate Law in California

The simple answer is that you evict them for non-payment of rent. There are, however, too many procedural steps that must be followed exactly to be laid out in this kind of internet Q&A. Nolo Press puts out a pretty good do-it-yourself book on evictions: http://www.nolo.com/products/the-california-landlords-law-book-lbev.html I would start by getting a copy. If anything in it is unclear or otherwise over your head, however, I would hire a lawyer to help you. In the end it will be money very well spent compared to the costs, delays and even potential liability to your tenants if you mess up an eviction.

I agree. The book's title is "The California Landlord's Law Book: Evictions" and the author is attorney David Brown. In particular, I'd point out that evicting longer-term tenants may require 60 days' notice, but that you don't need a reason (such as non-payment of rent) to terminate a month-to-month tenancy.

I'd have an attorney review the rental agreement closely. If they have agreed in a lease to 30 days notice, you can probably give them 30 day notice to terminate their month to month tenancy, even if they have resided in the property over a year. (But I would double check that.)

You can give a three (3) day notice to pay or quit for nonpayment of rent, but if they pay the rent within the proper time, they are still your tenants. I suggest serving both notices, after consulting with an competent real estate attorney who has handled some of these eviction matters before.