This works to remove bluetooth devices that fail to remove:

Try setting up your Windows 8 system so that ghosted / hidden devices appear in Device Manager.  http://www.mytechguide.org/12179/remove-hidden-devices-from-windows/ (or see below if link has died).

Then, go to Device Manager, find the problematic bluetooth device, right click and hit uninstall.  Then go to Devices in Windows 8, hit the (-) sign to remove.  That should complete uninstall.

Before pairing bluetooth device again, ensure that bluetooth driver in Device Manager is Enabled.

How to display hidden device (ghosted) drivers in Windows?

By now, you already know Windows’ Device Manager (by default) doesn’t display ghosted devices. To show hidden devices in Device Manager, follow the simple steps below.

1. Click on Start to open the Start Menu.

2. Right-click on Computer and select Properties. (You can also use the keyboard shortcut Windows Key + Pause Break to open System.)

3. From the System window that opens, find and click on Advanced system settings from the left-side panel. This will open the System Properties dialog box.

4. In the System Properties dialog box, click on Environment Variables button. This will open another dialog box.

5. Now under the User variables for <YourUsername> box, click on New.

6. Type devmgr_show_nonpresent_device in the Variable Name field. Type 1 in the Variable Value field.

7. When you open Device Manager (type devmgmt.msc in Start search box and hit Enter) and select View > Show hidden devices, all the ghosted devices will be shown with their icons faded away.