diff --git a/mod/lesson/deprecatedlib.php b/mod/lesson/deprecatedlib.php
index b1929f66a34..7eccd695c7c 100644
--- a/mod/lesson/deprecatedlib.php
+++ b/mod/lesson/deprecatedlib.php
@@ -29,3 +29,10 @@ function lesson_get_completion_state() {
     $completionclass = \mod_lesson\completion\custom_completion::class;
     throw new coding_exception(__FUNCTION__ . "() has been removed, please use the '{$completionclass}' class instead");
 }
+
+/**
+ * @deprecated since Moodle 4.0
+ */
+function lesson_add_header_buttons() {
+    throw new coding_exception(__FUNCTION__ . '() has been removed');
+}
diff --git a/mod/lesson/locallib.php b/mod/lesson/locallib.php
index 0d089adbaf1..967d726d89e 100644
--- a/mod/lesson/locallib.php
+++ b/mod/lesson/locallib.php
@@ -567,37 +567,6 @@ function lesson_menu_block_contents($cmid, $lesson) {
     return $bc;
 }
 
-/**
- * Adds header buttons to the page for the lesson
- *
- * @deprecated since Moodle 4.0 in favour of tertiary navigation.
- * @todo MDL-73545 This will be deleted in Moodle 4.4
- * @param object $cm
- * @param object $context
- * @param bool $extraeditbuttons
- * @param int $lessonpageid
- */
-function lesson_add_header_buttons($cm, $context, $extraeditbuttons=false, $lessonpageid=null) {
-    global $CFG, $PAGE, $OUTPUT;
-
-    debugging('lesson_add_header_buttons() is deprecated in favour of tertiary navigation.', DEBUG_DEVELOPER);
-
-    if (has_capability('mod/lesson:edit', $context) && $extraeditbuttons) {
-        if ($lessonpageid === null) {
-            throw new \moodle_exception('invalidpageid', 'lesson');
-        }
-        if (!empty($lessonpageid) && $lessonpageid != LESSON_EOL) {
-            $url = new moodle_url('/mod/lesson/editpage.php', array(
-                'id'       => $cm->id,
-                'pageid'   => $lessonpageid,
-                'edit'     => 1,
-                'returnto' => $PAGE->url->out_as_local_url(false)
-            ));
-            $PAGE->set_button($OUTPUT->single_button($url, get_string('editpagecontent', 'lesson')));
-        }
-    }
-}
-
 /**
  * This is a function used to detect media types and generate html code.
  *
diff --git a/mod/lesson/upgrade.txt b/mod/lesson/upgrade.txt
index 8894913f4da..0ce6fa5997c 100644
--- a/mod/lesson/upgrade.txt
+++ b/mod/lesson/upgrade.txt
@@ -1,5 +1,9 @@
 This files describes API changes in the lesson code.
 
+=== 4.4 ===
+
+* The deprecated `lesson_add_header_buttons` method has been removed
+
 === 4.0 ===
 * Deprecated the function lesson_add_header_buttons in favour of tertiary navigation.