LibreNMS Disable Slack Transport

Hello everyone,

I tried slack transport for our test Libre setup by using UI, Global Settings >> Alerting Settings >> Add Slack URL. Now, Libre keeps posting alerts in our channel, which is nice, but as this was a testing setup, now we want to disable it. We simply deleted the transport using the same interface and steps but Libre still pushes alerts to our slack channel, which is annoying. My question is, how we can disable it once and for all?

my validate.php;

Component Version
LibreNMS 1.40-5-g4e79465
DB Schema 251
PHP 7.0.30-0ubuntu0.16.04.1
MySQL 10.0.34-MariaDB-0ubuntu0.16.04.1
RRDTool 1.5.5
SNMP NET-SNMP 5.7.3

====================================

[OK] Composer Version: 1.6.5
[OK] Dependencies up-to-date.
[OK] Database connection successful
[OK] Database schema correct
[WARN] Your install is over 24 hours out of date, last update: Tue, 05 Jun 2018 09:28:13 +0000
[FIX] Make sure your daily.sh cron is running and run ./daily.sh by hand to see if there are any errors.

dist-pollers.php -l pollers;

±—±------------±--------------------±----------±----------+
| ID | Poller Name | Last Polled | # Devices | Poll Time |
±—±------------±--------------------±----------±----------+
| 23 | librenms01 | 2018-06-18 14:57:38 | 23 | 157 |
| 9 | librenms02 | 2018-06-18 14:55:19 | 3 | 17 |
±—±------------±--------------------±----------±----------+

Many thanks!