some files were uploaded in error. How can we delete them?

will not let me put up screenshot.   The files were uploaded via desktop  there is no "trash can" and these files must be deleted (she meant to put them in dropbox).   Just need to know how to delete at this time.  If there is no way to delete we must know before we set up a permanent account.  I can't imagine the took the ability to delete.
Thank you in advance,
Lori