Write an article based on this "Back up your files. Power down the MacBook. Flip the MacBook over on a work surface. Remove the ten screws securing the back panel. Lift the lower panel. Disconnect the battery connector."
If you are replacing your hard drive, you will be reinstalling OS X. Since your files are stored on the hard drive you are removing, you will need to back up any files you want to transfer to the new drive. This will make the operating system reinstall as painless as possible. See this guide for detailed instructions on backing up your files. Remove the power adapter cable. You must power down the Mac before opening the panel, or you run the risk of shorting out your components. Note: You cannot remove the hard drive from any MacBook Pro with the Retina Display, as these use integrated flash memory as opposed to traditional hard drives. You will be accessing the back panel of the MacBook. Set it on a table or workbench that gives you easy access without having to bend over. These run along the edges of the bottom panel. The exact location of these screws varies by model, but there are always ten. You will need a Phillips screwdriver to remove them. There are usually two types of screws:  Seven 3 mm Phillips Three 13.5 mm Phillips The 13" MacBook Pro may have slightly different screw configurations, but there will still be ten screws. Wedge your fingers into the gap between the vent and the lowercase and pry the panel up. You will release two clips securing the panel as you do so. This connector provides power to the logic board, and should be disconnected before continuing to prevent shorting out any components. It is black and located along the edge of the logic board, and is the largest connector attached. Make sure to pull the connector straight out so as not to damage the connection.  If there is a tab connected to the battery connector, use it to pull it out of the socket. If there is no tab connected, you can use a spudger or cocktail pick to push the connector out.