Remove An Apple Divice

Hi, my name is eni, I'm an user in Clash Of clans (in android.. and ios).
I have a problem, I'm playing in android, but I'm add my sister device
(Apple 5s) for me, to buy GEM, I'm Charge my sister account 100$ and for
some problem, I can not buy GEM, now I want remove my sister account to add
another device apple account.

*Clash of Clans say: The Current village has already been linked,. The
linking can be done only once.*
Now how can I UNLINK my sister device ?
Because I need to link my clan to my own Apple ios 4. Now how can do that?
I'm very sad. I can't add my own apple device to play game.
i have both, my andorid mobile and apple 5s. i'm unistall clash of clans,
but i see error code :

*The Current village has already been linked,. The linking can be done only
once.*

Please Help me.