What should you do if your child is scared of the potty? First of all, you want to figure out what fear is. Is your child scared of the noise that the potty makes? Is your child scared of the water in the potty? Or is your child simply uncomfortable and feels like he's going to fall in the potty? Those are common fears that many parents deal with.
If your child is scared of the noise that the potty makes, then you can tape the flusher so it doesn't flush when he's in there. Or you can remove all the water from the potty so that it doesn't make a noise when he goes pee. If your child is scared of the water or scared of getting splashed, again you can drain the toilet so that there isn't any water in the toilet, or you can put toilet paper over the water so as to buffer the sound. Or, believe it or not, I had one child who wore goggles because he was afraid of being splashed in the face.
So whatever the fear may be, address that so that your child is willing to use the potty. If your child is scared of falling into the potty, make sure you get a potty seat that fits on top of the toilet. This will make the hole smaller and is comfortable so that your child is stable. Also, you can provide a step for his feet to rest upon so that his feet aren't dangling. Again, he can feel stable and more comfortable while he's sitting on the potty. Even if your child is scared of the potty, you can resolve the issue so that he can ultimately be potty trained.