I quit a job in California. After my resignation, they sent me an email requesting that I confirm I turned over all employer property, and asked me to sign an agreement with the following:
Do I need to respond at all? Can I strike that if I don't agree to that last statement? How should I handle this?
The time to form contracts is when both parties will benefit. If they're offering something in return for this signature, you get to decide whether you want to take those benefits.
If not, just say you're not interested in forming new agreements with them. Last time I was in a meeting with a manager trying to get a similar form signed, the phrase "this looks like a contract and you're not offering anything in return" was useful, or "if this is merely a summary of what we've already agreed, then there is no need for a signature"
Contracts you've already agreed to (i.e. the original employment contract) would still apply, so look there to see if there's anything relevant to this situation (which, as others have mentioned, might still get overridden by actual laws)