I had this before, though not through a direct communication. Someone had gotten my email credentials somehow and installed a company’s app and made an account. When I went through the support pages on the company’s site to find out how to delete the account the only listed way was through the app itself.
They were accommodating and helpful when I emailed the company about it though. I just told them that I can’t agree to the privacy policy and thus cannot install the app but still need the account to be deleted. They did it.