CCleaner (from Pirisoft) would do the job nicely - nab it from here
. It is free so you don't have to pay for it.
Windows does have its own disk cleanup utility as well so have a poke around with that. For 'optimizing' your hard disk, that would involve defragmenting it - either try Windows' own built in defragmenter or grab Auslogics Defrag (also free) which will do the same job. Diskeeper 9 is brilliant but not free.