If your account has been accidentally removed from the admin role on Facebook, you can get it back again. If your account is hacked and the hacker removed the admin, you’ll need to submit a request.
There are many ways you regain ownership of the account, which are given below.
Reclaim a Page if the account is hacked – If you are the owner of the account and you’ve been removed as admin from the account, visit facebook.com/hacked to regain access. Then you need to open a help page titled ‘I am having an issue with accessing my page’ where you can select the page and click on the Send button.
If an Admin has removed you – In that case, log in to your account and then open the ‘Reporting a violation or infringement of your rights’ help page, select copyright, and then ‘Continue with your Copyright report’ and click on the Send button. You will also need to provide the contact information about you and the organization you work for. And then, select the content you want to remove, provide proof of your copyright or copyrighted work, confirm the declaration, and then click on the Submit button.
But if your Facebook page is deleted by a rogue admin, you can recover it. There is an option to recover Deleted Facebook Page through a help article. You will have to send a request to Facebook through a help article to get the deleted Facebook page back to its original form.