How can I reduce the 70 GB of storage that is classified as system space on my MacBook?

Solution 1:

You can use the build-in Storage Management.app for inspecting what file is consuming large amount of disk space

Another software Daisy Disk is very useful for disk space visualising, so you can easily find out the large directories or files by checking the sector area (for directories that contains its files and sub directories)

Solution 2:

I have the same issue but just solved it. You can use from here Disk Inventory X. It will shows you the detail information about your storage. From there you can delete unuseful files.

Solution 3:

You can use OmniDiskSweeper to analyse the files that occupies most of your space and at the same time can delete files too .I hav solved my mac storage issue using this software.