Changing cat litter is a dirty and unsanitary job. Potty training your cat eliminates the need for cat litter boxes. Some cats take to the training quickly while others may take longer to adapt to the new process and then there are some who will reject the whole process. There are two main phases of potty training your cat. The first phase is introducing your cat to the toilet. The second phase is eliminating the litter box and conditioning your cat to use the toilet. The most important thing to remember you have to keep the step sizes small enough as not to disrupt your cat's life. If at any time your cat starts peeing in other areas, you're pushing him/her to fast; back up a step or two and try again - slower. Also, remember: lid up, seat down, and leave the bathroom door open.
First, move your litter box into the bathroom, if it's not already in there, next to the toilet.
Put something under the litter box to raise it about and inch. Wait a few days so your cat can adjust to the change. Next, get something else to raise it a little higher. Wait a few days for your cat to adjust. Continue this until the bottom of the litter box is level with the top of the toilet seat. The reason for this process is to condition your cat to jump into the litter box and eventually jump on the toilet first to get into the box.
Next, get a bowl that fits the inside size of the top of the toilet bowl opening at its widest point. Metal bowls are best. Now, move the litter box directly over the toilet seat. Remove whatever you used to elevate the box. Wait a few days...