These methods will cause no harm to the squirrels as they work to eliminate the problem.
Cayenne Pepper or Chili Powder
Squirrels detest the scent of cayenne pepper and chili powder, so sprinkling it around the areas that are affected by squirrels will keep them away. Locations where this is most effective include gardens, flower beds, grass, entryways, in bird seed and on wood. Reapply the powder over areas that have come in contact with water, such as rainfall or from sprinklers or a hose, and continue applying until the squirrels are no longer a problem.
Olive Oil
Applying olive oil to metal surfaces such as bird feeder poles, porch railings and fences will keep squirrels away. For hard-to-reach places, using a spray can of Pam will work just as well. The squirrels won't be able to walk along these surfaces. Even after a heavy rain the oil should remain in place. Reapply the oil as needed until the squirrels stop coming around.
Ammonia
Often squirrels get into attics, basements, ceilings and in between walls. Soaking a rag with ammonia and leaving it in these areas or near vents will get the squirrels out of these areas. The ammonia should be mixed in a container with one part ammonia to three parts water. After a week or so remove the rag, soak it in the ammonia again, and put it back in the affected area.
Moth Balls
Squirrels don't like the smell of moth balls, and these can easily be placed in areas inside and outside of the home. They can be left in these places for years, and it is ideal to use them in storage units, attics, basements, under patios and in other places where people don't often go.