iMessage delete sync issue between iPhone and Apple Watch

Greetings Anwar_Irfan,

Welcome to Apple Support Communities. Do you have iCloud for Messages enabled on the companion iPhone? If not, that would be the reason that messages deleted from the iPhone aren't deleting from the Apple Watch. You can check and enable this feature using the steps from the Apple Support article: Set up iCloud for Messages on all your devices - Apple Support

Set up iCloud for Messages on your iPhone, iPad, or iPod touch

1 . On your iPhone, iPad, or iPod touch, go to Settings > [your name] > iCloud.

2. Do one of the following:

• iOS 16, iPadOS 16, or later: Tap Show All, tap Messages, then turn on Sync this [device].

• iOS 15, iPadOS 15, or earlier: Turn on Messages.

Any messages currently stored in iCloud are now accessible on your device, and any new messages you receive on your device will be stored in iCloud.

3. To make sure you can see your messages on all your devices, also check the following:

• iMessage account: On your iPhone, iPad, or iPod touch, go to Settings > Messages > Send & Receive. Make sure that you’re signed in to iMessage with the same Apple ID. You can choose which email addresses and phone numbers you want to send and receive messages from on each device.

• Text message forwarding: If you want to receive SMS and MMS messages on all your devices, go to Settings > Messages > Text Message Forwarding on your iPhone. Turn on text message forwarding for each device. For more information, see the Apple Support article How to forward SMS/MMS text messages from your iPhone to your iPad, iPod touch or Mac.

4. To see messages stored in iCloud, open the Messages app.

Let us know if this helps you.

Best regards!

I'm on my fourth Apple Watch and the messages have never deleted from my watch when deleted on my phone, MacBook Pro, or iPad Pro. I don't think it's possible, but it is a bit annoying so I'm hoping someone can prove me wrong.

Hey there Anwar_Irfan, 

That's great news.  

Have a good one!