The answer to above’s question is answered by a research done where Images were uploaded on famous social networking websites like Facebook, Hi5, Bebo, LiveJournal, MySpace and many others and Each of the image url was noted. Then Later All of the images were deleted. 

It was Found that many website’s did not delete the photographs even after 30 days, while some did instantly.

For our experiment, we uploaded a test image onto 16 chosen sites with default permissions, then noted the URL of the uploaded image. Every site served the test image given knowledge of its URL except for Windows Lives Spaces, whose photo servers required session cookies (a refreshing congratulations to Microsoft for beating the competition in security). We ran our initial study for 30 days, and posted the results below. A dismal 7 of the 16 sites failed to revoke photos after 30 days

Here are the Results of the research -

Did not remove photographs even after 30 days - Facebook, Hi5, Bebo, LiveJournal, MySpace

Removed Photographs in 30 days - Blogger, Friendster,  Tagged, Picasa

Websites which removed photographs instantly -  Orkut, Windows Live Spaces, Photobucket & Flickr

Users need to be very careful while uploading images on The social networking websites as You never know that your image, even after you delete, may be still present you may even fall into some kind of trouble!

Thanks OnlyGizmos, Mashable and  Light Blue TouchPaper