Why can't the newly bought Samsung 9300 be deleted by SMS or pictures?

If you want to edit, modify, move or delete a file, method 1: Open [File Management] to find the file you need to delete, then press and hold the file to display the option immediately, and click Delete in the option; Method 2: In the picture browsing interface, when you turn to the picture to be deleted, click anywhere on the picture. If there is a trash can icon on the display, click this icon to delete it. If you don't find this icon, you can click the function key that comes with your phone, and then click Delete. I use LG phone, so I don't know where the function keys of your phone are.