California rental lease early termination notice period requirements

[PK Adi]

Hi,

My tenant signed an year lease for the period 07/01/2023-06/30/2024 but gave me a lease termination notice on 07/23/2023 without moving in stating financial reasons. They want to terminate the lease on 07/31/2023.
They are expecting their security deposit back.
Is there a law in California that mandates a minimum period for the notice, like 30 days? If such a clause exists, can you please share the links that supports it?

Thanks in advance.