TL;DR Don’t leave things off if it will create a gap (including a gap between your education and first job).
A large gap on your resume (including a large unexplained gap between education and first job) is far worse than non-applicable experience, so I would never remove something just because it doesn’t apply to the position you’re seeking.
That said as a rule of thumb I believe you only need to include the last ten years of professional experience (good to double-check this—career seeking advice changes over time), and your “non-applicable experience” is outside of this window so you’re good to omit it.
But if this weren’t the case, I would strongly recommend keeping it on your resume. It can mean the difference between getting an interview and getting summarily rejected based on your resume alone.
The reason gaps are so bad is that hiring managers only have your resume and somewhere between 1-6 hours of interaction with you to decide whether to hire you, a commitment that is costly for the company, and risky if you turn out to be a bad hire—risky in terms of both cost and legal risks. It’s far preferable to not hire someone who’s a bad fit than to hire and later fire them.
So hiring managers have to do all they can to limit the risk to the company and that means being very selective in the hiring process. Anything that could possibly be a negative on your resume (and a big question mark like a long unexplained gap is exactly that) means it’s time to pass on your resume and interview the dozen other candidates who’s resumes didn’t raise any red flags. It sucks, but it’s reality.
So don’t add unnecessary red flags to your resume like false gaps due to leaving a job off your resume.