Reset PC in Windows 8
Windows 8 includes a feature called Push-Button Reset that gives you options for returning your PC to a known configuration. You can use this to recover from a problem, or to return it to the factory state. Remove Everything and Reinstall Windows. This option, is called Reset your PC is useful when you want to get a completely fresh start on a PC, with no previous files or configuration retained. The Remove everything and reinstall Windows option permanently removes your personal files and apps from the PC and returns Windows 8 to its original state. That original state is either a clean install of Windows 8, or the OEM factory default configuration, depending on the media used for the operation.

 Table: Elements preserved and returned to default state
 Preserved                                                         Returned to Default
 Activation State                                                  Everything
 Files on non-WIndows drives (optional)                 Non-Windows drives (optional) 

Activation State
The only element of your configuration preserved by a Refresh is the Windows activation state. This is to help provide a better post-Reset experience. In most cases Windows should be activated automatically at the end of Reset without user action.One exception to this is on a PC where you usedd the Add features to install the Pro Pack or Media Pack to upgrade your Windows Edition.

Remove Everything and Reinstall Windows Steps (Reset)
* Open the Charms bar (Press Windows+C) while on the desktop
* Click on the Settings button
* Open the General section of PC Settings
* Remove everything and reinstall Windows. If you want to recycle your PC or start over completely, you can reset it to its factory settings.

Getting Started

File Removal Options:
Just remove my files =
This option performs a quick format of the disk. This deletes the table on the drive that contains filesystem pointers to your data files. It does not delete the actual file data or touch the parts of the diskwhere the data exists. The behavior of this option will vary depending on if the drive is encrypted with BitLocker. If the volume is not encrypted, then this option performs a full format of the disk and writes zeroes to every sector. This will take quite a long time. This is simiar to running the command format.exe c:\ /p:0

Fully clean the Drive =
If the volume is ecrypted with BitLocker, only a quick format is performed, as that wipes all of the 
information necessary to decrypt the disk. With no way to decrypt the disk, the data is effectively lost. Note that this procedure will take much longer than the quick format. It takes a long time on a large hard drive. 
* To proceed, click the Reset button at the Ready to reset your PC step
*
At this point the PC is restarted into full-screen progress screen
* T
he next step on a PC where the Pro Pack or Media Pack was installed you will need to enter your Product Key. Notice that there is a Skip button here. This would enable you to complete the Reset without entering your key. That can be useful if you are selling a PC and want to retain a retail Windows 8 license that you installed on it.Once you are past the License Terms you will find yourself in the Windows Welcome, with all the same choices as you saw during the Windows 8 setup. At this point, the PC has been returned to the original Windows 8 state.