iCloud storage
If I delete my iMessages from iCloud will it delete them from my phone too?
Question marked as
If you have Messages in the Cloud set up (see Set up iCloud for Messages on all your devices ) then yes, your deletions will synchronise to all devices.
Keep your messages up to date with iCloud
Because your messages are in the cloud, if you send, receive or delete a message on one device, those updates appear everywhere. You see the most up-to-date version of your messages, no matter where you access them.