If a user sets their 'Track read/unread posts' personal profile setting to

'No', delete all of their read records.

user/edit.html

@@ -148,6 +148,17 @@ if (isadmin()) {
     choose_from_menu ($choices, "autosubscribe", $user->autosubscribe, "") ?>
     </td>
 </tr>
+<?php if ($CFG->forum_trackreadposts) { ?>
+<tr>
+    <th><?php print_string("trackforums") ?>:</th>
+    <td><?php
+    unset($choices);
+    $choices["1"] = get_string("yes");
+    $choices["0"] = get_string("no");
+    choose_from_menu ($choices, "trackforums", $user->trackforums, "") ?>
+    </td>
+</tr>
+<?php } ?>
 <?php if ($CFG->htmleditor) { ?>
 <tr>
     <th><?php print_string("textediting") ?>:</th>

user/edit.php

@@ -191,6 +191,12 @@
                     set_send_count($usernew,true);
                 }
 
+                /// Update forum track preference.
+                if (($usernew->trackforums != $USER->trackforums) && !$usernew->trackforums) {
+                    require_once($CFG->dirroot.'/mod/forum/lib.php');
+                    forum_tp_delete_read_records($USER->id);
+                }
+
                 add_to_log($course->id, "user", "update", "view.php?id=$user->id&course=$course->id", "");
 
                 if ($user->id == $USER->id) {