Hello boydooo,
Got it.
Just to confirm, are you following the below steps to delete the attachments:
Delete multiple attachments from a contact or conversation
1. In a message conversation, tap the contact's name at the top of the screen.
2. Tap Info 
.
3. In the Photos section, tap See All.
4. Tap Select, tap the images you'd like to delete.
5. Tap Delete, then tap Delete Attachment to confirm.
If so, let’s next go into photos and empty the recently deleted folder. Normally, deleted photos are kept from 30 days to allow time to recover the photo if it was deleted by mistake. By manually deleting them, you will immediately remove them. You can do that following the steps below:
Recover deleted photos or videos
1. Open Photos and tap the Albums tab.
2. Tap the Recently Deleted album under Utilities.
3. In iOS 16, iPadOS 16.1, or later, use Face ID or Touch ID to unlock your Recently Deleted album.
4. Tap Select.
From here, you can select photos to recover or you can delete all. If you delete all, they will be gone from your devices, and your account permanently.
Kindest regards.
