Deleting old messages on MacBook without affecting iPhone in iCloud sync

Messages are taking up lots of space on my macbook pro. I belive you can unsync a device from icloud and delete the messages to keep them your iphone-- But I'd like to keep my macbook synced. Is it possible to unsync on macbook, delete old messages, and then resync to icloud? Or will it delete those messages on my iphone upon resyncing?

Is there a way I can delete old messages on macbook without deleting off iphone while staying synced after?

[Re-Titled by Moderator]

Original Title: If I unsync mac from icloud and delete old messages, will they be deleted from my iphone if I resync?