When you pair a Bluetooth device with your cell phone or computer, it asks for a PIN number or a security code. The connection between both the Bluetooth devices is established on the basis of this code. If you are no longer interested in connecting both the devices in the future, you should reset the code. By resetting, the Bluetooth devices will delete the existing code and will ask you to retype it in case you ever decide to pair them again.
Go to the menu on your cell phone. Search through the connectivity options and select the 'Bluetooth' option. In the Bluetooth menu, you will see the devices that your phone is currently paired with.
Use the directional keys on the phone to select the device that you want to unpair. You will see a number of options in the context menu. Select 'Delete/reset PIN'. This will reset the security code back to the default code, which is usually '0000'.
Disconnect the connection of the Bluetooth devices simply by selecting the 'Remove'/ 'Delete' option on your cell phone. If you want to pair the devices in the future, you will have to type in a new security code.