Over a period of time your hard disk gets cluttered up with temporary files, logs, internet files etc and becomes slower
To tidy up these files and to reclaim disk space Windows includes a tool called Disk Cleanup
To launch the tool follow the instructions below for your version of Windows:-
Windows XP, Windows Vista and Windows 7 - Click Start > All Programs > Accessories > System Tools > Disk Cleanup
Windows 8 - Right mouse click on Start Menu button and choose Control Panel > System and Security > Administrative Tools > Disk Clean-up
Windows 10 - Click Start > All apps > Windows Administrative Tools > Disk Clean-up
If you have multiple drives it will first ask you which drive you wish to cleanup, this is normally C:
The tool will then scan for any files that can be removed
Once completed it will display a list of all the files to delete and the space they are taking up,
Tick all the items shown in the list - except Compress Old Files (Windows XP) or System Compression (Windows 10) and then click OK to remove these files automatically