it can be deleted by using the shopify API
https://shopify.dev/docs/admin-api/rest/reference/customers/customer?api[version]=2020-04#destroy-2020-04
need to Create new private app and generate the key" and “Password” field, you can find “ADMIN API PERMISSIONS” heading. need to provide “read and Write” permission for “Customers”. and save that App.
after that we need to pass that url in form and with the action delete method
Note : Only those users can delete their account that does not have order history
if any one wants Help regarding this , you can contact me - on skype - binarydata.aspdeveloper
Thanks