Which isn't even legally permissible, there is no way to 'give it back' (although you could stop using the title) - it can only be taken from you, which has to be done by the king on recommendation of the prime minister.
These "honours" (knighthoods, peerages etc.) should now be referred to as "disgraces". Liz Truss handed out an honour for roughly each four days of her incumbency as Prime Minister, nearly all to crazies from the extreme right of the Conservative Party. We already have way more peers than can actually be stuffed into the House Of Lords.
Boris Johnston’s attempts to knight his father and Russian oligarchs donating money to the conservatives for titles are examples of this.