Figured you'd want a quick answer but here you go

1. Remove the Ants:
Carefully open the soil outside or in an area away from their grow space. Wearing gloves, they should gently break apart the soil to expose the ants and their nest.
Manually remove as many ants and eggs as possible.
2. Use Heat or Cold:
Heat Treatment: Spread the soil out in direct sunlight for several hours or even a day. The heat will make the ants uncomfortable and force them to move. Alternatively, they can heat the soil in the oven at a low temperature (around 150-180°F / 65-80°C) for about 30 minutes. This will kill any ants or eggs, but be careful not to overheat and harm the soil's beneficial microbes.
Cold Treatment: Place the soil in a sealed container or plastic bag and freeze it for a day or two. Freezing will kill any ants and eggs.
3. Natural Ant Repellents:
Mix diatomaceous earth into the soil. It’s harmless to plants but will act as a barrier for ants.
Watering the soil with a solution of neem oil or a diluted soap solution (biodegradable and safe for plants) can also deter ants.
4. Ant Bait:
If they notice the ants are still around or starting to invade the area, setting out ant baits in a separate location can help draw them away.
Once the ants are gone, the soil should be safe to use.