How can I free up storage (System Data) on my MacBook Pro?

Justmycupoftea wrote:

How can I clear "System Data" in my MacBook Pro Storage?

You'll need to download a 3rd party storage management tool. What Apple provides is useless.

It's taking up a huge chunk of space and I can't run Photoshop. How do I know which files I can delete? Are "unsupported" apps safe to delete? What else?

If you can't even run apps, then you probably won't be able to download any new ones. Your hard drive must be totally full.

You'll need to manually locate large files and delete them. And since you're already totally full, any storage task like this is going to be extra slow and take a long, long time to complete. Deleting files is a great example. As you delete files, your "system data" will probably increase. You'll have to wait a day or so for the files to really be removed.

You may be able to force the issue by manually deleting local snapshots in Disk Utility. But to be clear, if you're at that point, then you're totally, critically out of free storage. Forget about deleting apps. Those are far too small. You need to delete at least 100 GB. You may need to archive files to external storage.

Here are the instructions for freeing up storage on your Mac: Free up storage space on Mac - Apple Support

You can not delete System Data.

and here is some more information on the subject:

How to free up ‘System Data’ and other storage on your Mac