Help with removing code from old theme

I recently switched my builder from Avada to Divi after my website crashed.

I deleted Avada, but some of the old code is still showing up at the top of each blog post. (Old fusion code)

Is there a way/plug-in to remove this code all at once?

There are about 300 blog posts, so I’d love to not need to do it manually.

 

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