Google Photos - deleting photos

What happens when you delete a photo

• If you delete a photo from the web (photos.google.com), the photo is deleted from the site and from all your devices. The photo can restored, if you want to, within 60 days - from the menu, select Settings -> Bin, select photos and restore.
• If you delete a photo in the Google Photos app on your mobile, the result is the same as above - it would be deleted from all your devices and from photos.google.com
• If you free up space in the Google Photos app, photos and video are deleted only from your device.

Disable Backup & Sync temporarily

When you are about to shoot photos/video and may not retain all photos and video from the shoot, you may temporarily disable backup & sync and then enable it again after deleting the unwanted ones (this would prevent items that are eventually deleted from getting backed up unnecessarily).

This option is available here: Google Photos app -> Settings -> Backup & Sync -> toggle off Backup and Sync.

Note that this disables Backup & sync of all Google apps, so it's a bit inconvenient if you plan to delete photos the next day but would like other Google apps like Drive to sync data between devices.