I couldn't figure out a way to do this so I just deleted my organization and the app I submitted that was nearing the end of the approval process. My LLC was formed with the state and I have an EIN. Right now I can't create an organization because it is saying that the EIN doesn't match the name (it does), so perhaps I have to wait a bit since the EIN is too new.
Update: I was able to create a new organization and upload the app again and submit it for review. So if anyone ever has to switch business entity type, deleting the organization and then creating a new one and reuploading is one way to do it. Not ideal. Hopefully there is a better way in the future.
We are trying to work through this same issue now. I think you are supposed to be able to do it here: https://www.facebook.com/help/contact/1540812909361378
However, we have tried it, and it hasn't worked out yet. Contacting support, we have been re-directed 7 times before having our support ticket closed claiming we have contacted them multiple times. We only contacted them once, but perhaps different departments had each opened separate tickets before re-directing us to the next department. I'm not sure what the issue was, but finally, after some persistence, we were told we had to get permission from our Organizations "Financial Admin", but there are only two of us in the organization listed as admins, and I guess neither of us are considered "Financial Admins" for the account. We are going to keep working at it but we aren't able to update our entity's tax information, so I'm expecting to have tax issues this year if they payout to our old entity this month. This process with Oculus Support has been more difficult than working with the federal government.
We might just start focusing our time more on our Pico and SteamVR versions, because it's difficult and slow to get anything changed with Meta. In addition to the entity and tax info, we have been trying to update some of our photos and descriptions in our app store page on Meta, and that is also quite the process.