There are 3 functions in Excel to do this:
Clear Formats and
Clear All removes content and all formatting (i.e. Bold/Italic/Underline, Borders etc as well as the colours)
Clear Formats removes all formatting, leaving the cell content.
Clear Contents removes cell content, leaving the fromatting.
In Excel 2010 the buttons are located on the right hand side of the
Home ribbon bar, under the
These can be accessed by the following key combination (do these one after another, not at the same time):
Clear All Alt -> h -> e -> a
Clear Formats Alt -> h -> e -> f
Clear Contents Alt -> h -> e -> c