My question involves business law in the state of: California
Long story short:
An investor's assistant approached me, a medical licensed provider, to open an outpatient clinic. I agreed and became the CEO but held no shares. The business was managed poorly and the assistant was fired and the investor stepped in with other investors. During this time, a lot of shady things were going on and I quit. They wouldn't remove my name from the business so it was a messy process, but it was finally (somewhat) done.
The problem is, the investors aren't allowed to close the business as they don't have a medical license, which indicates they had been running the business, in some form, without a medical provider. So they had been threatening me (with other things) and want me to sign a document agreeing that I'll close the business at the end of the year. I don't want to do this because 1) I have NO idea what they had been doing since I left. 2) I don't want to become associated with them again and what they have/are doing, which is the reason why I left. 3) I don't know why they're asking me to do it at the end of the year (initially they told me maybe around May. I'm suspecting they took some kind of business loan with the Covid 19 small business protection...).
I don't know what my obligations or rights are regarding their demand. I never agreed to close it, as they claimed. They continue to threaten me that they didn't report me to the boards, or can take me to small court claims (regarding something else), even though they told me they won't be anymore. If I ignore their request, what happens? Are they allowed to close the business themselves? Do they get "caught" and punished? I feel I am risking more to sign it, but don't know how to respond.
Thank you for any help and insight.

