How can I remove an SEO override from my source code?

[HUNTEDFOX]

At some point last year I allowed an app (SEO Ant, Tiny Image SEO or possibly another) to  "update my meta data".  What they did instead of updating my actual listings-

I have spent C O U N T L E S S hours and weekends back to bak researching and editing every single of my 450 individual product listings, only to find that the SEO is being overwritten by something they embedded in my source code that over writes my actual Shopify product listing edits.

Can someone PLEASE help me sort out how to remove this override so that I own the right to update my SEO on my own?