Changing number?

Hi, it's going to be a slightly intricate question, hopefully someone can help.

I want to delete my current WhatsApp account and register a new account with a new number. The reason being is I have someone on my blocked list who persists to message me using different numbers and I have to keep blocking them. The only way this person can contact me is through WhatsApp.

I want to know if I can register a new account with my new number, then remove that SIM card from phone and carry on using my old number for ordinary use and using WhatsApp? Will this stop that person messaging me on WhatsApp? What other implications are there, if any?

Thanks