We prepared a script for you which should kill service worker.
Add that script and load your website.
We suggest to leave it for a while so other users who subscribed will be able to kill service worker as well.
<script type="text/javascript" src="https://firepush.io/assets/scripts/shop_worker_fix.js"></script>
Please note that every web push service provider has to create that service worker.
Even Shopify does when merchant activates admin push.. so... it's not something we can avoid.