Exiftool is pretty useful.
exiftool -Rights='New Owner Info' image.png
Some additional bits (2023-01-13) from here:
# List all metadata of a file (exif)
exiftool -s screenshot.png
# Remove GPS coords in a file
exiftool -gps:all= filename.jpg
# Clear out all metadata
exiftool -all= filename.jpg somesong.mp3
Some alternatives: https://imageoptim.com/mac and https://exiv2.org.