why can't I delete an old photo from my iPhone?

Delete photos or videos

When you delete photos and videos, they're sent to your Recently Deleted album for 30 days. After 30 days, they'll be permanently deleted.

If you use iCloud Photos and delete photos and videos from one device, the photos and videos will be deleted on your other devices.

If you add photos to your iPhone or iPad by connecting your device to your computer, you can't delete them directly from your device in the Photos app. If the Bin button  is grey when you try to delete a photo from your iPhone or iPad, you may need to stop syncing photos from your computer. Find out how to stop syncing photos from your computer.

How to delete a single photo

1. Open Photos.
2. From the Library tab, tap All Photos and select the photo or video that you want to delete.
3. Tap the Bin button , then tap Delete Photo.
4.  

How to delete multiple photos

1. Open Photos.
2. From the Library tab, tap All Photos, then tap Select.
3. Tap multiple photos, or slide your finger across multiple photos to select more than one.
4. Tap the Bin button , then confirm to delete the items.
5.  

In iOS 16.1, iPadOS 16.1, and later, you can start an iCloud Shared Photo Library and invite up to five contacts. Anyone can delete, add or edit items in the Shared Library. If someone else deletes a photo or video from the Shared Library, it no longer appears for you, either. Only the person who added the photo or video to the Shared Library can permanently delete or recover it from the Recently Deleted folder. You have 30 days to get a photo or video back from your Recently Deleted album.

Delete photos on your iPhone or iPad – Apple Support (AU)

JaneenHi wrote:

why can't I delete an old photo from my iPhone?

What happens when you try? What exact steps are you taking? Are you getting any error messages? If you want help other than generic boilerplate, it's important to provide details.