On my desktop I used to have the main taskbar at the top of the desktop and set to auto-hide.  Then one day it moved to the left side of the desktop.  I tried to move it back (by drag and drop) and I can't.  I get a message that I can only have one auto hide taskbar on the top side.  But, there is no taskbar there.

How do I remove the Phantom Taskbar

Presuming you can see the task bar to which you refer, try opening it and see if you have any option to close it.

   Do you have the taskbar locked?  If so, you will not be able to move it back until you unlock it.  Go to Conrol Panel - Taskbar and uncheck the Lock Taskbar checkbox.  Then drag the taskbar to where you want it.
   My guess is that you accidently moved it by dragging it and then locked the taskbar.