How to Reformat Macbook Pro from USB

Follow the steps below:

1. Create a bootable drive using a USB for OS X Mavericks. 
2. Plug in your bootable USB drive and Restart your Mac while holding the Option key. Make sure to keep it pressed down!
3. When it restarts, you’ll have a few options. Choose your USB Installer.
4. Next, select the Disk Utility option.
5. In the window, at the top of the left bar, select your Mac’s Main Drive.
6. Next to the First Aid button at the top, click the Erase button. 
7. Now, near the center of the window, select the Format drop-down list and select “Mac OS X Extended (Journaled)” as the type.
8. Click Erase (this will erase your main drive) and allow time for the drive to format.
9. When it’s finished, close out Disk Utility and select “Install OS X” from the menu.
10. Select your main drive and install a brand new OS X Mavericks on it. 

Follow the install instructions and enjoy your newly clean-installed OS X Mavericks.