Open the Google Photos app or go to photos.google.com
Sign in to your Google account if needed
Select the photo or photos you want to delete
Tap or click the Trash/Delete icon
Confirm the deletion if prompted
To delete multiple photos, press and hold one photo, then select others
To delete all photos in an album, open the album and select the photos individually
To permanently remove deleted photos, go to Trash or Bin
Open Trash or Bin
Select the photos you want to remove permanently
Tap or click Delete forever
To restore a deleted photo, open Trash or Bin and choose Restore