Messages are sending to a contacts email instead of their number.

When i text my friend, it always sends to her mac book email instead of her number. I am not able to start a conversation with her number even if i select that option. I have also tried creating a new contact with the emails and removing them from her original contact card leaving only her number. And it still links the two contacts somehow and only send the message to her email. I have also turned off imessage to see if that would work and now i cant even send an sms to her number. How can i stop messages from sending to an email instead of the number?