Received in text message? If so, the fast way is CLOSE the text message. When you want to chat with them again or they with you, start a NEW chat. Think of text conversations like phone conversations: begin-chat-end (with this end piece defined by closing the chat). The modern approach is leave text conversations open for up to forever, which is akin to never hanging up the phone in a phone call: all the junk and the few goodies people text each other just pile up and up and up some more.
I think I recall that even when you delete a chat in Messages, the release on iCloud space is not immediate but takes a while. So if that weak recollection is true, don't expect to see an immediate reduction in cloud space used. However, it will process eventually and all that space eaten up by cat videos, etc will finally be released.
If not text messages, define received.