Facebook & Duolingo
I currently use Facebook to sign into my Duolingo account. Does this mean that I won't be able to sign into Duolingo if I permanently delete my Facebook account?
In your profile under settings you can enter a password which you can than use to sign into duo using your username. Once you did this and checked that it works, you can go to profile and disconnect your duo profile from your facebook account. Afterwards it doesn't matter at all what you do with your facebook account.