I cannot guarantee this answer applies to High School, but in REAL baseball the batter/runner is not out for retreating toward home without reaching home. There is a “Sandlot Myth” that a runner on a force play cannot retreat because he is “forced to advance” but that language in the rule book is only meant to set up the force play at the base ahead of the runner and is not intended to prohibit a runner retreating. We see this all the time when R1 backs up to avoid a tag by the 2B in order to make the DP harder to make. Nothing illegal there and the Batter/Runner between home and 1B is no different. If the Batter/Runner retreats beyond home plate, he is out for abandoning the basepaths.
