User switched to Android and my phone still tries to send iMessage

Ok, this is driving me nuts. My cousin switched from her iphone to some lame android and my phone kept recognizing her as an iphone user and sending her imessage. We've read forums, googled etc and I've seen where they say to have the former user log in to her iTunes account and deactivate the device. She said she logged on to her account in iTunes support and it didn't say anything about deactivating but she just deleted the number from her account. She no longer has the phone so there isn't anything we can do with that.

On my end I've deleted her contact, re-added it, changed her number to just mobile... What are we missing? We've logged in to her account and nothing. She has nothing on her account, no device, no numbers. If I didnt text her everyday it wouldn't be a big deal, but it's annoying to wait for my message to fail to send to her thru iMessage and then have to resend it as a text.

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PLEASE HELP