For different browsers the removing the cookies depends differently for example if you are using
Firefox
Use >> Tools >> Clear Private Data >> Select Cookies >> OK
In IE
Tools>>Intenet Options >> Delete Cookies ()from Temp Internet Files Options)..
Also there are some free ware who can do the complete process them selves.. try googling for CCleaner it is a good one to keep your pc optimized and also deleted those cookies when ever you run it rather of any browser you are using..
For any further assistance with the pc and computer support try
http://www.iyogi.co.uk