How to delete pictures from dropbox?

if you want to delete all photos in dropbox, press command A (select all) and right click delete.  

... Go to dropbox.com. - Log in. - Delete. Installing the Dropbox client is ... folder. - Wait whilst Dropbox downloads the entire contents ... folder. - Synchronise Dropbox - whereby it deletes the photo on ...  

... or anything else from your Dropbox account is to install the ... website and delete the photo from your account.