Messages in iCloud backs up and syncs all SMS and iMessage messages on your iPhone and lets you use them on other Apple devices, as long as you're signed in with the same Apple account. Keeping lots of old messages in iCloud is also unnecessary and takes up storage space. Here's how to delete old messages in iCloud on iPhone.
How to delete old messages in iCloud
Step 1:
If you want to delete a specific message from iCloud, you'll have to delete it from the Messages app on one of your devices.
You open the Messages app on your iPhone, then on the message you want to delete, swipe left and select Delete to do so.
To delete multiple messages at once, click Edit then click Select multiple messages . Next, click on the messages you want to delete and click Delete to perform.
Step 2:
After deleting the message, you need to delete more in the trash.
You click on the 3 dashes icon in the Messages app and select Recently Deleted . Then you also need to delete all these messages .
Step 3:
After you completely delete the messages including the trash, go to Settings and select Apple Account , then tap iCloud .
Tap Messages then tap Sync Now .
Step 4:
If you don't want to sync iPhone messages with other devices or backup, you need to turn off iCloud messages.
In the Apple Account interface, you also click on Messages. Then we turn off Use on this iPhone . Then you click Off and download the messages .
Tap on Manage Storage and finally tap Turn Off & Remove from iCloud and you're done.