Blocked external resource question

Hopefully this question isn’t confusing but I’m using Semrush for a site audit and they listed that I have “669 issues with blocked external resources in robots.txt” and that the cause is https://s7.addthis.com/js/300/addthis_widget.js and a script more precisely. I don’t have AddThis installed on my website so how do I remove this script?

Thank you in advance

The page I need help with: [log in to see the link]