I need someone to help me close a WhatsApp group

I created a WhatsApp group with my old phone number to assist students coming from my country to the UK. The person I made an admin of the group removed me as an admin due to concern I have over security as they have turned the group into currency exchange group. I don't want to be involved in it, my phone number is linked to the group. Fraud has happened on the group and I won't wait till a major one occurs that will be linked to my number. Thank you.