Sometimes old files can be safely deleted. Temporary files for example. If you have such files, there is an easy way to do this with only Microsoft tools. You may have to install the Windows Resource Kit for your Version of Windows.
forfiles command, for which you might have to install the Windows Resource Kit, you can list files matching some criteria and execute a command for each found file.
forfiles -p "C:\<path>" -s -m *.* /D -<days> /C "cmd /c del @path"
will delete all files in
<path> who are older than
<days> (mind the