SSN Validity for Tax Purposes

Hi,

A few years ago, I was awarded a green card and, in this context, a social security number. Since then, I left the United States and the green card is no longer valid.

I am looking to set up an LLC with just me as the owner, so no other members. I understand that I have to get an EIN for this operation.

When you fill out a form on the IRS website to get an EIN. It requests either an SSN or an ITIN. For these purposes, is my social security number still valid? even if I do not live in the United States or a US citizen anymore?

When I look at ITIN, it indicates that no one with an SSN should have an ITIN.

Can someone clarify for me what I have to do here?

Thank you!!