If point is at the end of a directory/ path component, make

DEL and M-DEL delete the entire component,

else delete a character or word, respectively, as normal.

(with-eval-after-load 'vertico
  (keymap-set vertico-map "DEL" #'vertico-directory-delete-char)
  (keymap-set vertico-map "M-DEL" #'vertico-directory-delete-word))