emacs wikiより

(defun kill-whole-line (&optional numlines)
"One line is deleted wherever there is a cursor."
(interactive "p")
(setq pos (current-column))
(beginning-of-line)
(kill-line numlines)
(move-to-column pos))

(define-key esc-map "k" 'kill-whole-line)

でM-kで1行削除