Why did you make it through Facebook in the first place? o.o
If its a fresh account just make a new one through runescape this time. Dont bot accounts connected to Facebook. I think you can only log into runescape without facebook if it was an older account with an email/name login and you connected that account to your facebook.
Last time I checked you never needed facebook to register a Runescape account. New accounts, however, do need an E-mail to be registered, but you do not have to connect this to your Facebook account.