If you use Mac OS Sierra on your MacBook Pro then there is an in-built feature which can take care of this, and no, we are not talking about the iCloud or any other paid cloud services. While those services are also a great way to create backup of your files and delete most of it from the PC, it entails a monetary charge which most users would rather avoid. So here’s how to use the in-built option to optimize storage on your MacBook Pro.
Click on the ‘Apple’ icon on the top left corner of your screen.
Click on the ‘About This Mac’ option.
In the window which opens up click on the 'Storage' tab.
Click on the ‘Manage’ button placed next to the hard disk symbol.
Select the option titled ‘Optimize Storage’. What this does is it automatically removes all the movies and tv-shows you have watched on your iTunes list, deletes all old email-attachments lying around in the downloads folder, and also empties the trash.
Once this process is completed you are sure to gain back quite a bit of space on your MacBook Pro. Of course if there are a few movies which you would like to save for a re-watch or a very important email attachment which may be required in the future, we suggest that you move them to a USB drive before running this operation.