If you have been using your Facebook account to log into the game and want to change to an E-mail based account you are currently able to choose between two ways to do it:

• Add a portable e-mail account: If you are using more than one Lords & Knights application (e.g. Classic and XMAS) this option will let you create an E-mail based log-in for the application you are currently using and remove the access via Facebook from it.
  You will still be able to use your Facebook log-in credentials in the other app.
  
  
• Remove Facebook access: This option will sever the connection between your game account and your Facebook account completely. You won’t be able to use Facebook log-in on any app. Your account will be accessible via E-mail log-in afterwards.

Your do not lose the option to link an account to Facebook in general.