Delete unwanted iMessages
Troubleshoot and rid your phone of unwanted iMessages
If multiple people are using the same Apple ID on different devices you may find:
You are receiving iMessage texts intended for someone else
Someone is receiving iMessages texts meant for you
You are receiving your iMessages texts as e-mails
The iMessage accounts on those devices are linked. Any messages sent or received through the Apple Messages app will be available on all devices using the same Apple ID.
To solve this, you need to disable the unwanted email addresses and phone numbers linked to iMessage on all devices that are using the same Apple ID.