Generally, it is quite difficult to get rid of unwanted cats since this sponsors the thinking that cats are not worthy. However, a number of adoption agencies can accept cats as they help the cat find a new home.
1 Additional Answer
If you need to drop off an unwanted cat, please take them to an animal shelter. They will be properly cared for while looking for adoptive homes. Just abandoning a cat is never a good idea because you won't know if they have food to eat or a place to sleep.