Ctrl+SpaceBar is a standard shortcut in Word for removing font formatting which is not part of the underlying paragraph style. Similarly, Ctrl+Q removes paragraph formatting which is not part of the underlying paragraph style.
To remove font and paragraph shading, only, you can run the following macro:
Sub ClearAllShadingFromDoc()
'Macro created by Stefan Blom, MVP, January 2015
With ActiveDocument.Content.ParagraphFormat.Shading
.Texture = wdTextureNone
.ForegroundPatternColor = wdColorAutomatic
.BackgroundPatternColor = wdColorAutomatic
End With
With ActiveDocument.Content.Font.Shading
.Texture = wdTextureNone
.ForegroundPatternColor = wdColorAutomatic
.BackgroundPatternColor = wdColorAutomatic
End With
End Sub
For assistance, see http://www.gmayor.com/installing\_macro.htm.
Highlighting applied via the Highlighting tool on the Home tab can be removed as follows: Select the whole document by pressing Ctrl+A and then click the arrow on the Text Highlight Color button and choose the "No Color."