u/DM_ME_RIDDLES

Hi, I recently emailed a company (US-based) requesting the deletion of my account with them (there was no way for me to just do this on their website myself) and my data because I was no longer using their service. Their support team replied back to me that I need to send a physical letter to their company headquarters in order to "withdraw [my] consent for [the company] to contact [me] for the continued collection, use or disclosure of [my] information."

Is this even legal? Do I have to post a physical letter at my own cost, or are they required to comply with my request over email? I'm not looking for legal advice just generaI advice because I am baffled and don't know what to do