macmacos
I have these 2 applications sitting in my Macbook Air Applications folder. I am currently running High Sierra and not planning to upgrade to either of these 2 versions. Is it OK to uninstall them or will their removal cause issues? Its currently taking up 11 GB and I want to free up some space.
You are safe to delete the Yosemite installer. It should not harm your computer if you delete it.
The remove the locks so that you can delete macOS system apps go to AppCleaner -> Preferences -> General Tab and Uncheck "protect default OSX Apps"
I just cleaned up garageband from macOS Sierra 10.12.5 which was shown as locked (system protected app) as shown in your image.
EDIT: As @leo said, please be warned that removing some system app like messages might break/ crash a whole set of applications or even the entire OS. SO please be careful about trying this
Best Answer
It is perfectly safe to delete unwanted macOS Installers - simply drag them to the trash [& empty it to recover the disk space], nothing further required.
You can always get them again if you need them.
Ordinarily, after a successful upgrade, the system would delete them itself.