1. Open the Charm bar by moving the mouse to one of the corner on the right or sliding in from the right, and select Settings.
2. Then, click or tap on Change PC Settings (more ways to open the PC Settings).
3. Click or tap on PC and devices. 
4. Click on tap on Bluetooth.
5. In the right pane of Manage Bluetooth devices,
   slide the Bluetooth slider to disable (turn on) or enable (turn off) the
   Bluetooth. The current on or off status is instantly reflected on the
   screen.
   
6. Close PC Settings

You can also use the method below:

1. Open the Charm bar by moving the mouse to one of the corner on the right or sliding in from the right, and select Settings.
2. Then, click or tap on Change PC Settings
3. Click or tap on Network.
4. Then, click on tap on Aeroplane mode.
5. In the right pane, under Wireless devices, slide
   the Bluetooth slider turn on the
   Bluetooth.