How can I recover deleted messages?

Do you mean backed-up to iCloud, or do you mean synced to iCloud (Settings -> iCloud -> Messages is turned on.) ?

If the latter, the messages cannot be restored.

If the former, you can restore the iCloud backup of your iPhone.

What does iCloud back up? - Apple Support (CA)

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support (CA)

Anything that is not synced to iCloud is included in the iCloud backup. So just change Settings -> iCloud -> Messages to off.