Grip the back panel with one hand

Grip the Macbook with the other hand

And pull the left side of the back panel AWAY from the HINGE side of the Macbook

This will require a lot of force. Don't be afraid to pull hard while keeping the Macbook steady and in position.

Repeat this with the right side of the Macbook

Once pulled from the hinge area, you may now remove the back panel and place it out of the way.