How to delete previously saved files to make more space on my external hard drive


#1

In June 2007 I purchased a WD 250GB  external hard drive to back up my PC files.  Since then it has been operating automatically and I have never had a need to restore lost files.  However the external hard drive is now 78% full and I would like to delete all unecessary files to make more space available on my external hard drive. 

Although my PC only has a 80GB hard drive my external hard drive is almost full (195GB of the 250GB has been used).  I am using Norton 360 software to back up my files.  Can anyone advise how I can delete previously saved files ? 

Thank you.