Level hardwood floor that was covered by baseboard
Make a cut using whatever small saw you have on hand--keyhole, reciprocating, oscillating--at each side of the opening just down to floor level. 
Use a chisel or other sharp tool to split the grain at floor level, shaving off a thin strip. 




_________ ___________________ ____________ &lt;-- top of protruding board 
_________|___________________|____________ &lt;-- floor level
               ^-- chisel here
         ^-- vertical cuts --^


Alternatively, install some plastic feet on the front of your wardrobe and forget about it.