It's very unlikely that your parents will just put you back into diapers but I guess if you want to wear diapers then you should just come out and tell them that you want diapers.
Your parents will likely not actually change your diapers anymore either since they did that a lot when you were a baby.
If you're bed wetting then either keep it a secret or tell your parents because if you're bed wetting they may buy you some absorbent underwear or diapers to keep the bed from getting wet.