How to free up storage space manually
Even without using the Optimized Storage features of Sierra or later, you can take other steps to make more storage space available:
Music, movies, and other media can use a lot of storage space. Learn how to delete music, movies, and TV shows from your device.
Delete other files that you no longer need by moving them to the Trash, then emptying the Trash. The Downloads folder is good place to look for files that you might no longer need.
Move files to an external storage device.
Delete unneeded email: In the Mail app, choose Mailbox > Erase Junk Mail. If you no longer need the email in your Trash mailbox, choose Mailbox > Erase Deleted Items.
Make sure you have a current backup before doing any housekeeping.
