Pasadena - inherited tenant eviction procedures

[Boris Suchkov]

We are looking at a duplex on Pasadena, CA. The front unit is vacant and the back unit has a tenant who has been there for 9+ years (month-to-month rent agreement). The back unit is in bad shape (no immediate danger, but it's likely something major will break sooner rather than later) so we would like to serve notice to the back unit tenant upon closing and proceed with renovations ASAP.

Can anyone recommend the letter/legal forms to use? A sample would be great.