Drop someone from my Netflix account?

2 months ago I gave my "Netflix account" to a "friend" (family account, my dad pays)
And I have no contact with her because she talked about me behind my back and insulted me for no reason. (XD)
So I was not allowed to give the account to anyone but with her I made an exception. Now I do not want to have you in the account anymore because she does not deserve it in my opinion. I can't change the password because I need a reason for that and I would get in trouble if I passed it on.

"I can't change the password because I need a reason for it" - No, you can just change that. Netflix does not ask why you do that. Why should they?

My dad should know but ned xD

Just be honest with your family and let the password change, for being so honest and having said it, you will probably get less trouble than if you find out yourself or something.

Change the password with the reason that you should change passwords every 6 months or so anyway. Just do a full paranoid and say you've just seen such a documentary, your dad will let you change, alone to put you down.