Double Login Password? (Fb/Bubble)

Hello, I want to double check if you guys think this is right because I don’t want to mess with user credential:

I wanted the user to be able to delete his account after a password check, What I discovered is that if the user is logged in with Fb, he can’t check his password because it is an inaccessible Fb password.

So I created the “reset password” button that allows the user to reset the password… Now I found out that the user can Log in with is Fb account or providing his credentials email/new password.

Something strange with it or all is good?

Thanks!

ps. I know there is something similar here (Google sign-up but want to change my password and login), but I want to be sure about the double login thing…