In emacs, as we open files, a lot of dired buffers get accumulated. I personally find them a nuisance after a while specially during longer emacs sessions. Killing them one by one using C-X k would be quite tedious. Fortunately there is better way to kill many buffers at a time.

For this we list all the buffers using C-X C-b. The list opens in a new buffer so we need to switch to this buffer using C-x o. Now we need to mark all the buffers that we wish to kill by typing d. As we mark, a capital D appears alongside the buffers' names. After all buffers to be killed are marked, just press x and all the buffers will get killed.