When you have a Bluetooth Mouse or Headset Devices which you add on
your Surface Pro 2 Devices, it can happen that something went wrong with the installation routine.
Or it is just not working. Ok, no problem, lets reinstall it .... Oops, when you go to PC Setting > Devices,
and try to remove the headset or mouse, you cannot remove the device because the remove button is
greyed out. Try reconnecting the Device to the tablet results in the error
“Adding your device failed. Remove it from your PC first then try again.”
Ok, what now? Try the following:
Press Windows + X keys from keyboard and click Device Manager. Make sure that bluetooth driver is Enabled.
You may need to display hidden device (ghosted) drivers in Windows 8.1 and remove it.
Go to Desktop mode, click “Libraries” in the taskbar, right-click on Computer, and select Properties.
In System control panel, click Advanced System Settings link from the left pane.
Click on “Environment Variables” button, click on “New” under the “User variables for <***theUsername***>” box,
devmgr_show_nonpresent_device for Variable Name and 1 for the Variable Value, and click OK.
Open Device Manager again, select View > Show hidden devices, and right-click on the hidden device and select Uninstall.
that should do the Trick