You can delete your own posts. Click on the title of the post and it'll take you to a page where the image and the comments are all on one page and if it's your post there should be a red box below the image that says delete. I believe if it has made it to the popular page then you cannot delete it.

Thanks ! :D

I can confirm about making it to the popular page. If you want one deleted that got to popular, you have to email the admins to ask them to delete it.