Whenever the free space on one of your windows drives gets low then one option is to empty your recycle bin. Well, this works fine - but Windwos stores an recycle bin for every user on the system who has deleted something. To delete the all recycle bins of all users on the c:\ drive with one simple command do it like that:

Since windows stores recycle bins for every user on on every local disk you have to repeat this command for all local drives on your harddisk to get rid of all deleted data.