Microsoft BitLocker enabled when Windows 10 is shipped.
Dell and Lenovo systems that ship with the Windows 10 operating system and are equipped with Trusted Platform Module (TPM) capability will have Microsoft BitLocker encryption enabled from the factory.
It has been found that once the device is registered to a Active Directory domain - Office 365 Azure AD, Windows 10 automatically encrypts the system drive. You find this once you reboot your computer and are then prompted for the BitLocker key.
To recover the key and be able to un-encrypt your device simply follow the instructions below.
Once you have the laptop unlocked you can simply switch off BitLocker if necessary.This can be done by typing "Manage BitLocker" in the search bar and opening the BitLocker management screen.
1. Azure Active Directory is currently in the classic portal so login here: https://manage.windowsazure.com with your credentials and select your Active Directory Name
2. Select Users at the top then search and select the user that the computer is assigned to.
3. Once the user profile appears, select Devices > Change the View drop down box to Devices > Select the computer Hostname (computer name) > Select View Details in the bottom
4. The BitLocker Recovery Key will appear in the window here