Throw the training wheels away. They are absolutely useless in teaching a child to ride a bike. They instill bad habits that will have to be unlearned once the training wheels come off. I'm all for starting even toddlers on strider bikes and older kids and adults on a bike with the seat somewhat lower than normal. Some people remove the pedals but I don't think that it is absolutely necessary.

My grandson learned to ride a bike later than most kids. I taught him to ride in a single afternoon by having him coast down a gentle hill in my back yard with the seat low enough that he could easily rest the balls of both feet on the ground. Within an hour he was coasting with his feet up and getting a fair idea of directional control and braking. I put the pedals back on and we spent another hour or so getting that coordination down. After a break, we went to a large empty parking lot behind the school and he was able to ride without assistance. He practiced turning and braking using markings on the pavement as references. By the time his legs gave out, he was riding fairly well.