How do I file as a non resident in California?

If you did not live in CA (permanent residence - domicile) but had CA source income (worked in CA or own rental property in CA, for example) then you can generate a CA non-resident return in the "My Info" section (see steps below).  

If CA was not your resident state and you did not physically work in CA or have any other CA source income you don't need to file in CA.  Here is a CA reference for the definition of "Non-resident" and more examples of CA source income. 

If you were military go here for special filing rules.  

1. My Info
2. Edit your information 
3. Select your resident state (home of record, if military) 
4. Continue
5. Still in "My Info" scroll down to "Other State Income" 
6. Answer "Yes" you earned income in another state
7. Select CA
8. This will generate the CA non-resident return
9. Continue
10. Complete the rest of federal sections
11. Prepare State
12. Start/Continue CA state interview
13. In the CA interview you will be asked to allocate to CA only the CA source income