When I　open a new email, and try insert a picture. On the opened window, there are always an old photo and can’t be deleted there.

It have confused me for more than one hour.

I also can see the photos by clicking “change photo” on my account icon in the google+. The link is: select profile photo/your photos/photos from posts/

At last, I find that I should delete from the google+ account. Here is the details:

https://support.google.com/plus/answer/2622947?hl=en

Manage your photos

You can delete any photos that you’ve added for a place by following these steps:

Sign in to Google+.
Click the Home menu in the top left and select Photos.
Find the album named either “Google Maps Photos” or “Photos from posts.”
Select the photo you want to delete.
The photo will open to a full-screen overlay view. At the top of the screen, click the trash button.