How to locate and remove untraceable code from a website header?

hello, I’m sure people have gone through the struggles of removing code from the top part of the header of their website. They could do this simply by fixing an extra space in the snippet, correcting grammar, or placements. My situation is a lot more different. In this case, I have code that is visible on the TOP HEADER of the website that isn’t even traceable. Meaning, I checked every file where it has been suggested to be located in, but it’s not any where to be found. if someone knows how to find these hidden codes deep in their system files, it would be very appreciated.

See the attached screenshot.