How do I quickly uncoolor all text marked in blue?

Hey there,

Is there a quick way to change all the text in my blogposts that I previously chose to mark in blue into a no-color option (black basically, but no-color would be better since some of it are headers which are supposed to show up in red)

I changed themes and the blue looks very messy in the new theme. Website is https://www.GuitarHippies.com

Would appreciate help,
Thank you very much!