Two simple steps:
- Trap them. Animal control agencies often have cat-sized traps to loan. Canned cat food and sardines make good baits where you’re not likely to catch a skunk or other wild animal; otherwise, try catnip.
- Take them to the nearest shelter that will rehome or permanently house them, or euthanize them if all else fails.
Alternatively, have them neutered and vaccinated and confine them to your own property in a predator- and escape-proof enclosure.
Do not leave them out on their own. Cats are domestic animals, and prolonging their homelessness to the detriment of your neighbors, other pets, and wildlife is almost as irresponsible as abandoning them in the first place.