You can usually go to Online Store > Preferences and find it there.
If it was hard-coded into the theme, it should be in your theme.liquid file. In that case open that up and search "fb" to locate the script and remove. (Or comment it out first if you're not sure)
Thank you for your response. But I already checked the "theme.liquid" file and I didnt find any fb scripts. It is very frustrating, because of the old fb-pixel I cant avertise, my new fb- pixel doesnt collect no data.
I'm having the same problem (proflacasse-boutique.com or https://prof-lacasse-shop.myshopify.com). I have inserted by mistake an additional Facebook pixel and can't delete it. I've searched it in every code page. How can I remove the extra one (27089xxxxxxxxxx).
what other files could it possibly be in? I'm having issues with shopify staying connected to facebook most likely because shopify won't let go of the old fb pixel. I've uninstalled the fb pixel, there's no code anywhere I can find that has any reference to it yet fb pixel helper detects it on my website, stonetreasuresbythelake.com.