Open the Photos app
Select the photos you want to erase
Press Command + Delete
Confirm the deletion
Open the Recently Deleted album
Select the photos again
Click Delete All or Delete Selected
Confirm permanent deletion
To erase photos from Finder, locate the files
Select the photo files
Press Command + Delete
Empty the Trash
To remove photos from iCloud, delete them in Photos while iCloud Photos is enabled
Check other apps or folders for duplicate copies
Back up any photos you want to keep before deleting