"This item cannot be deleted because it is still referenced by other pages"

Hey,
I created some master pages to change the layout of my site with some content types with different page layouts.
After some time i got finalized my site layout. Now i thought that i should remove the garbage data from site like other content types, master page and page layout. So i prefer to go into SPD(Sharepoint Designer) and press delete button after selected item. What is this!!!!
"This item cannot be deleted because it is still referenced by other pages"
I thought might be on my site somewhere i am using these things so i did double check for everything and try again but its kick my a** again with the same error message.

Then again i went to great GOD google and found this is most popular error message when you are going to delete you content type, Master page and page layout etc and also get solution there. So to help you guys i am written the same thing here.

Steps:-
1. Create a new sub-folder in the masterpage document library.
2. Move the master page to the new folder (I did this by using SharePoint Designer)
3. Just delete the complete folder.
Yup, my master page finally gone from the document library!!!

You will feel relax after this if you had created a lot of sample items in you site.