I understand your concern, but that's not how the law prohibiting it works. That just says that unfair commercial practices are prohibited, and it is unfair to use aggressive practice, such "any onerous or disproportionate non-contractual barriers imposed by the trader where a consumer wishes to exercise rights under the contract, including rights to terminate a contract or to switch to another product or another trader". https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A...

So, requiring an ID check for termination, for no other reason than to make it more difficult than necessary, would still fall under this prohibition.