@Lisaplayzsims4 Have you tried quitting without saving yet? That's the easiest approach at this point, and hopefully your sims won't lose all their relationships this time around.
If your current save is from after the adoption scenario started, you can try loading the automatic backup save instead. Open Documents\Electronic Arts\The Sims 3\Saves, and you'll see a folder with the name of your current save and a second folder with the same name plus a .backup extension. Rename that save and delete the .backup, and it'll be available to load from the Main Menu.
As far as I know, there's no way to stop an adoption in progress with NRaas mods. However, you can use Total Annihilation to remove only the adoption worker; running MC > Status > Career on all the service sims (from the City Hall menu) will list each one's service assignment.
You can also use MC to adopt a child or pet. This provides the same outcome without the chance of the scenario getting stuck.