With the AI settings added to Extended Edition, this achievement and all the other "Defeat the XXXX" achievements become a lot easier than they would've been if the original AoM had achievements. Set however many AI opponents you need for each achievement, all of them with the "No AI" setting. Once you've started the match, just go around destroying their town centers and killing their villagers. Rinse and repeat for each variant of this achievement.
This doesn't affect any other achievements, however, so you'll still need to play proper games if you want the achievements for playing as or against certain gods, building wonders, etc.