Step on them! Okay you must mean an ant's nest or ant infestation in the home. I have had good look by pouring boiling water on top of an inconveniently located ant hill but for ant infestations in and around the home a licensed pesticide company or one of the approved products in the pesticide aisle of your garden center might be best. Ants in the garden and ants on your plants are usually not doing much damage.  Keep growing, Marianne Binetti