There is a reason why I referred you to the tutorials, because "erase event" is the wrong way to go there.https://forums.rpgmakerweb.com/index.php?threads/parallel-processes-once-per-entering-a-map.40566/
I'll look for the "Erase Event" command.
Did you not read the title of the tutorial you linked?
ONCE PER ENTERING
if you use erase event, your actors will still be reset and gain another set of items whenever you return to that map, because the event will still run once per entering the map.
I already said above you need to learn how to switch off an autorun or parallel process.
That is called "switching off" because you need to use a switch to do this, either the control self-switch command or the control switch command. Because only that will disable the event permanently to never repeat.

