you need to set a flag at the end of the script and set that sprite's person id to the flag you set.
From
Sierra's XSE Scripting Tutorial:
Flags are very useful when you need an event to only occur once or if you want a person to disappear.
Let's say you set flag 0x200. If you want an overworld to disappear, we have to assign the set flag (in this example, 0x200) to the overworld's people ID in Advance-Map. I'll go into more detail on that later.
Many flags are used within the game already. If you plan on leaving scripts that are already in the ROM, you'll need to be more careful on what flags you use, because flags can only really be used once.