I have that exact same Pixel 3 Caseology screen protector (and wrote a short review about it). One of the protectors also shipped with a defect. I wonder if that’s why they ship in packs of two? There doesn’t seem to be a reasonable reason otherwise.
As far as removing them, I don’t think there’s any special trick. Mine broke when someone bumped into me at a bar. I just used my fingernails to gently pull up the edges. You want to do it slowly, otherwise you’ll break the tempered glass further.
My protector only had one small crack in it. If your screen is completely shattered, it could be a different story.