Yes, indeed. California taxes all of your income no matter where you earn it. If you have income taxed in another state (such as DE), then you can get a CA credit for that by filing a CA Schedule S, tax paid to another state with your CA return. You will need to file a DE return for that income and a CA return for your total income.
See this Turbotax item about filing for more than one state:
https://ttlc.intuit.com/questions/1900021-when-would-i-have-to-file-returns-in-more-than-one-state
