Remove obsolete `db/cmp-date-property' function

init.el

@@ -710,7 +710,6 @@ With given ARG, display files in `db/important-document-path’."
              endless/org-ispell
              db/org-agenda-list-deadlines
              db/org-agenda-skip-tag
-             db/cmp-date-property
              hydra-org-agenda-view/body
              org-babel-execute:hy
              db/org-timestamp-difference

site-lisp/db-org.el

@@ -117,23 +117,6 @@ If OTHERS is true, skip all entries that do not correspond to TAG."
         next-headline
       nil)))
 
-(defun db/cmp-date-property (prop)
-  ;; https://emacs.stackexchange.com/questions/26351/custom-sorting-for-agenda
-  "Compare two `org-mode' agenda entries, `A' and `B', by some date property.
-
-If a is before b, return -1. If a is after b, return 1. If they
-are equal return nil."
-  (let ((prop prop))
-    #'(lambda (a b)
-        (let* ((a-pos (get-text-property 0 'org-marker a))
-               (b-pos (get-text-property 0 'org-marker b))
-               (a-date (or (org-entry-get a-pos prop)
-                           (format "<%s>" (org-read-date t nil "now"))))
-               (b-date (or (org-entry-get b-pos prop)
-                           (format "<%s>" (org-read-date t nil "now"))))
-               (cmp (compare-strings a-date nil nil b-date nil nil)))
-          (if (eq cmp t) nil (cl-signum cmp))))))
-
 ;; A Hydra for changing agenda appearance
 ;; http://oremacs.com/2016/04/04/hydra-doc-syntax/