How to ignore specific MacOS software updates?
Just go up to the menu bar and hit Update>Ignore Update (or the keyboard shortcut is apparently just the delete key).
Try using the command "softwareupdate --ignore" in terminal. You can first start with a "softwareupdate -l" to get the actual names of the updates (usually something like iPhoto-9.1...) and then use the ignore command to stop them from showing up.
To see everything that binary can do, try running "man softwareupdate".
Alternatively, you could delete the applications and Apple won't try to update them anymore.