diff --git a/admin/settings/subsystems.php b/admin/settings/subsystems.php
index f2b50d5c49113..81408bf3acc15 100644
--- a/admin/settings/subsystems.php
+++ b/admin/settings/subsystems.php
@@ -15,8 +15,6 @@
 
     $optionalsubsystems->add(new admin_setting_configcheckbox('messaging', new lang_string('messaging', 'admin'), new lang_string('configmessaging','admin'), 1));
 
-    $optionalsubsystems->add(new admin_setting_configcheckbox('messaginghidereadnotifications', new lang_string('messaginghidereadnotifications', 'admin'), new lang_string('configmessaginghidereadnotifications','admin'), 0));
-
     $options = array(DAYSECS=>new lang_string('secondstotime86400'), WEEKSECS=>new lang_string('secondstotime604800'), 2620800=>new lang_string('nummonths', 'moodle', 1), 15724800=>new lang_string('nummonths', 'moodle', 6),0=>new lang_string('never'));
     $optionalsubsystems->add(new admin_setting_configselect('messagingdeletereadnotificationsdelay', new lang_string('messagingdeletereadnotificationsdelay', 'admin'), new lang_string('configmessagingdeletereadnotificationsdelay', 'admin'), 604800, $options));
 
diff --git a/lang/en/admin.php b/lang/en/admin.php
index c9836726c5ac4..03b4beff8c99c 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -274,7 +274,6 @@
 $string['configmaxevents'] = 'Events to Lookahead';
 $string['configmessaging'] = 'Should the messaging system between site users be enabled?';
 $string['configmessagingallowemailoverride'] = 'Allow users to have email message notifications sent to an email address other than the email address in their profile';
-$string['configmessaginghidereadnotifications'] = 'Hide read notifications of events like forum posts when viewing messaging history';
 $string['configmessagingdeletereadnotificationsdelay'] = 'Read notifications can be deleted to save space. How long after a notification is read can it be deleted?';
 $string['configminpassworddigits'] = 'Passwords must have at least these many digits.';
 $string['configminpasswordlength'] = 'Passwords must be at least these many characters long.';
@@ -747,7 +746,6 @@
 $string['mediapluginyoutube'] = 'Enable YouTube links filter';
 $string['messaging'] = 'Enable messaging system';
 $string['messagingallowemailoverride'] = 'Notification email override';
-$string['messaginghidereadnotifications'] = 'Hide read notifications';
 $string['messagingdeletereadnotificationsdelay'] = 'Delete read notifications';
 $string['minpassworddigits'] = 'Digits';
 $string['minpasswordlength'] = 'Password length';
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 25884fd0f222e..cc3fee8bf6a3f 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -2306,5 +2306,13 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2018051701.10);
     }
 
+    if ($oldversion < 2018051702.02) {
+        // Remove unused setting.
+        unset_config('messaginghidereadnotifications');
+
+        // Main savepoint reached.
+        upgrade_main_savepoint(true, 2018051702.02);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 3d4ab59925f49..b50278651c1ff 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2018051702.01;              // 20180517      = branching date YYYYMMDD - do not modify!
+$version  = 2018051702.02;              // 20180517      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.