VBA project explorer still showing the excel workbooks which are closed by the macro

I Found the answer myself sorry to waste some space here . I request to close these or delete these post, if you think its not neccessary Thanks !

   Dim Excel_workbook as excel.workbook
   set Excel_workbook = workbooks.open("somefile name");
   ' some code goes here 
   ' at the end write the below statement
   set Excel_workbook = Nothing 'worked, I found at the 12 page of google search

This is the link that helped me http://www.mrexcel.com/forum/showthread.php?t=50086