Open the Messages app
Tap Edit or Filters
Tap Recently Deleted
Select the conversations or messages you want to remove
Tap Delete
Tap Delete Messages to confirm
To permanently erase all deleted texts, tap Delete All in Recently Deleted
If Recently Deleted is not available, check whether the messages were already permanently removed
To clear message data from iCloud, go to Settings
Tap your name
Tap iCloud
Tap Messages
Turn off Messages in iCloud if needed
Delete any synced message threads from other Apple devices if they still appear
Empty deleted messages from any third-party backup apps if used