Were the appointments contemplated for the period beyond Mexico?
Maybe they are
Ah hear yuh! Just wanted to toss that out there before proceeding.
It's possible they were indefinite in nature ... the "performance review and assessment" of technical staff that have been referenced by several posters may also track that indefinite characteristic ... probably exist informally and ad hoc, rather than in a structured, documented format.
Reviewer: "So Anton, wha waz de scenes wid Mexico?"
Anton: "Dem fellas lapse ... plain and simple dey lapse!"
Reviewer: "So wha yuh suggest?"
Anton: "Steups ... fuh de most part, look fuh some new youths to blood."
To answer the question, assuming the appointments run, the Head Coach's resignation should be tendered.
I've suggested on here before that Anton should depart to ply his trade elsewhere. It's difficult to see what he gains
in terms of professional development from being in such an incestuous environment. Leave and return reconstituted.
A credible U-17 WC coach would/should catch the eye of foreign outfits.