If you have shared a whitelist with the wrong server or would like to unshare a whitelist for other reasons, you can easily run the /configure-whitelist unshare command. It will provide you with a list of whitelists and servers they are shared with and you can simply unshare by selecting the correct one.
While you can unshare a whitelist, we cannot guarantee that the server you have shared with has not already downloaded the whitelist data. If you are unsharing because you did not want to share a list that you are still collecting signups for, make sure to let the other team know that more data will come later.