Is it an Instagram? If so, confirm the email, then change it to something random, go back to the email you confirmed then you should get an email saying your email was changed and in the bottom it'd say "please secure your account" or something click that, then it'll give you two options it'll redirect you to instagram.com and make sure your not signed into anything, the options are gonna be like "Secure my account" or "It was me" click it was me, then to remove a facebook, add a facebook, go to facebook.com then remove it from there then go back to instagram relink it then sign out of your instagram and reset your password with facebook and your good. then put your confirmed email back on and confirm it again.