iPhone disabled and account deleted from iCloud

Your iCloud is your account. you can't remove one from the other, because they are the same thing. If you removed your iCloud account form the iPhone and as such the iPhone no *** get appears on your device list on iCloud, then you just need to restore the iPhone, and set it up again. That's the normal process. Removing the iPhone from your iCloud account was the correct thing to do.

Follow the steps here or have your sister follow the steps to restore the iPhone. so she can set it up again: link-> Restore your iPhone, iPad, or iPod to factory settings - Apple Support

For information relating to 'How to delete your Apple ID account', click here --> https://support.apple.com/HT208504

"What happens if I change my mind after I have requested that my account be deleted?

While your request is being processed, you can contact Apple Support [ https://support.apple.com/kb/HT201232 ] with the unique alphanumeric access code you received, and we’ll help you cancel your request. After your account is deleted, Apple can't cancel the request, reopen your account, or restore your data."

What did you do exactly?

What do you mean you "deleted your account form your iCloud"? Do you mean you removed your account from the iPhone 6?

Deleting the iPhone would of course require you remove your iCloud account from it. Then it can be setup again, and you can sign in with other account again during setup.

Please explain exactly what is happening, and what you are looking to accomplish.