You will need to make this entry in the state interview screens for California under the General info section. Proceed through the screens until you see the screen titled "Do you have a dependent you didn't claim on your federal return?". Select yes on this to screen to see the list of dependents listed on your state return.
On the next screen titled "Here's what we have for your dependents so far," you will see a chart that lists all the dependents on your state return. Select delete to the right of any duplicate dependent entries.