How do you evict an adult family member. We have had many issues with our 19 year old daughter and have tried everything during the past year. We asked her to leave as we warned her we would and she refused. When we called the police they said we would have to evict her. We live in CA, what is the process?

You need to do a written eviction.
I looked it up and California can have anywhere from a 3 day to a 90 day eviction depending on the circumstances.

California Eviction Notice

Overview of the eviction process
If the tenant doesn't voluntarily move out after the landlord has properly given the required notice to the tenant, the landlord can evict the tenant. In order to evict the tenant, the landlord must file an unlawful detainer lawsuit in superior court.

In an eviction lawsuit, the landlord is called the "plaintiff" and the tenant is called the "defendant."

An unlawful detainer lawsuit is a "summary" court procedure. This means that the court action moves forward very quickly, and that the time given the tenant to respond during the lawsuit is very short. For example, in most cases, the tenant has only five days to file a written response to the lawsuit after being served with a copy of the landlord's complaint. Normally, a judge will hear and decide the case within 20 days after the tenant files an answer.

The court-administered eviction process assures the tenant of the right to a court hearing if the tenant believes that the landlord has no right to evict the tenant. The landlord must use this court process to evict the tenant; the landlord cannot use self-help measures to force the tenant to move. For example, the landlord cannot physically remove or lock out the tenant, cut off utilities such as water or electricity, remove outside windows or doors, or seize (take) the tenant's belongings in order to carry out the eviction. The landlord must use the court procedures.

California Eviction Laws

You have to do the written notice with the right amount of days. Then when she refuses to leave you have to go to court and they then serve her with an eviction notice.

This is a Real Estate Law queston not Family Law. It doesn't matter whether the resident is a family member or a tenant. Once they have established residency, they have to be formally evicted.