How do I speak English without an accent?
You do not need to. Every English speaker has an accent, including speakers from the United States and the United Kingdom, and the practical goal is being understood rather than erasing where you come from.
You do not need to. Every English speaker has an accent, including speakers from the United States and the United Kingdom, and the practical goal is being understood rather than erasing where you come from. Work on the specific sounds that carry meaning in your situation, keep the ones that do not, and let a listener tell you which is which. If you want the best American accent apps for a particular sound, choose one that lets you repeat a single word and hear your own recording, then check that word in a dictionary with UK and US audio.
Record the same sentence twice, once before and once after listening to the dictionary audio, and keep both files so the difference is yours to hear rather than something a score tells you.