To Remove Appearance Overrides
In the QAT, click Clear 
Alternatively, on the Tools tab
Materials and Appearances panel, click
Clear.
In the graphics area, select one or more objects.
Note: Use Shift+Click to add unselected objects to the selection set. Use Ctrl+Click with selected objects to remove them from the selection set. To empty the selection set, click anywhere in unpopulated display space.
Click OK. The appearance override is removed.