Facebook login issue in Settings,help!

I have trouble deleting a Facebook account on Settings, my mom used my iPad and somehow her facebook registered in there and I can't seem to delete it, we entered her password but it won't work,I deleted the FB app and reinstalled, restarted my iPad and also rested all settings, and her facebook name is still on there lol..HELP I can't share bitstrips or other apps using my facebook, I don't know how that happened,she shared pictures from photo stream I'm guessing that started it,but how to end it? I've searched for solutions on apple community, I've seen most people having the same problem,but I couldn't find any helpful ways to fix it, I tried them all, I updated to IOS 7.1, I hoped it may removed it but it's still there,argh!! Please help me.

ThankYou :)

Naomi -