Just read this:
How can I delete my account? I f you log in to My Gransnet you can delete your account from there. This will delete: email, password and, if provided, first name, last name, postcode, date of birth, grandchildren's names, gender and dates of birth, your gender, registration IP, private messages sent.
And here is the GDPR info:
www.gransnet.com/info/privacy-policy-faqs
I have had myself totally removed from elsewhere by contacting them and saying that I want a total removal according to my rights under GDPR regulations.
Even Bannatyne's removed me eventually but it dad take a while.