[Here](https://www.gluu.org/docs/gluu-server/4.2/operation/faq/#revert-an-authentication-method) is what you can try.
It's always best to _test_ new ACR method in incgonito window / different browser.
Something like: Change your desired ACR in primary browser, keep that active....
Test in incognito window / new browser. If anything goes wrong, you can change back with primary browser.