How do I remove one of my family members?

Ok so you can't remove a family member from the game. But in the main menu, click on the area where it says "Click to change animals". Then near the top there will be a tree symbol. That's your family tree. You can't put your mate into another family. But you can with your children. So click the child you want to move and it will go to a different section. Once you have moved it you can't move it again.