Leaving school at 16 yr old isn’t considered “dropping out” over here. Also “drop out” doesn’t have the same connotations here either.
It's the same as in Australia.
There is politeness, consideration and connotations and then there is practical reality.
For example, when I write to applicant:
'Thank you for your application. After careful consideration, we have decided to go with another candidate for this position. But we will reconsider your application if another position becomes available. Thank you for applying and we are sorry we couldn't offer you the position this time. Blah, blah.'
It really means: 'I don't think you are good enough for this position, please don't apply again.'
Kids leave school in Australia in grade 10 because they don't want to be physicist or accountant thus thinking they don't need to finish grade 11 and 12 of high school.
Then they realize they don't really like working: as the kitchen hand, back breaking labor work, lifting boxes in warehouse, long hours, weekends, etc.
But they find out that most doors are closed to them, despite polite connotations like 'early school leaver for work experience', 'hard working', etc.
That's why we have night schools, adult high school completions, etc. You can call it whatever you want but at the end of the day: employers view things from different perspective.
As I said in previous post: I'm not gonna give advice on grounds of being supportive and polite; but advice on reality how employers view it and implications for job search.
Anyway, that's just my advice that I think is more helpful then just being polite and avoiding the truth between reality and politeness.
It's up to the OP to decide what to do.
Whatever it is: best of luck.