I think you're confusing things. What the X means (in Facebook as in almost any site or app) is to CLOSE a window, not to delete. Delete actions are important and shouldn't be placed in a spot where the user can accidentally click it, much less if they click it on purpose thinking they will actually CLOSE a window.
I think you should clarify what do you want to do first. If you're trying to close a window, then yes, top right is the perfect spot because most people is right handed so they won't need to cross the window to perform the close action (this is specially evident in mobile: if you apply the close button on top left, then you'll cover the screen with your hand to perform that action)
However, if you want to DELETE, just like your post says, then NONE of your options is recommended. Instead, you could have an action bar on top of the image which includes a proper delete icon and/or a delete text, or an "actions" block under the photo or as part of additional content (such as photo title, caption, description, and such, just like FB does). And once you perform such an important action, you need to have a confirmation dialog.
In short: if it's CLOSE, then you should use your second mockup, top right, just like Tohster said. If you want to DELETE, here's a quick mockup showing both options I mentioned (obviously, you should use one, not both at the same time)
I didn't understand from your question this was going to be applied on an ongoing action (add a picture), but an already performed action, since you can't delete what doesn't exist. What you're doing is cancelling an action , which is different, yet my reasoning still applies. See image for the FB app where you can clearly see the icon cancels an action, and compared to your image (and FB working on already uploaded content) where your icon actually CLOSES the window. Conceptually, they're always a CANCEL button. In the first case, they cancel the action of uploading an image, in the second case, you cancel the visualization of the element which was fired by a previous