This video and article will show you how to do a clean install of OS X Mavericks from USB.

Step 1. Create a OS X Mavericks USB drive. You can do that by following the 123myIT video guide here.

Step 2. Once installed, plug the USB into the side of your computer restart the Mac and hold down the ALT or Option key on the keyboard of your Mac.

Step 3. Use the arrow keys on your Mac keyboard to navigate to the USB drive that you have plugged into your computer. Once highlighted press Enter or Return.

Step 4. That will bring up the OS X Utilities menu. At this stage you can opt to format the hard drive with Disk Utilities. Make sure you backup your data before you do this as you will lose any data on the drive when you format it. If you want to know how to do a backup with Time Machine click here.

Step 5. Go back to Install OS X and follow the prompts. You will be asked to agree to Apple terms and conditions and you will also need to select the hard drive you want to do a clean install of OS X Mavericks on.

Step 6. This process should take around 30 mins depending on the speed of your Mac. The Mac will reboot a few times while this is happening.

Once the Mac restarts one last time and then you are done you will have to setup your Mac as if it was brand new from the Mac store. You will need to setup the country location, Wifi and there is also an option to transfer some files between your Mac and other computers. Then setup your Computer account.

For more information on OS X Mavericks you can check out the Apple official website here.