Found a 52.1GB file related to google in mac 'private' folder. can I delete this? I checked the storage on my macbook and discovered the 'system' was using nearly 150 GB.  

I looked around online and discovered the app OmniDiskSweeper. I gave it a go and discovered a massive file that appears to be related to google chrome, located in /private/var/folders/j9/T/com.google.Chrome/zip_cache-9F00A5C9-014F-4D48-AC13-2F74C26F4Fc7-31472-000034BBAF5DAD8A

Does anyone have any idea what this could be, and how it could be so large? can I delete it?

When i try manually searching for any of those files in finder, it turns up blank.  omnidisksweep is the only way I can see it (that I know of anyways) and thus the only way to delete it as well.  I really want to destroy this file but afraid to destroy some crucial thing on my computer.

Any advice greatly appreciated!
It's a cache file with a name associating it to the browser Google Chrome.

Anything under the path /private/var/folders/* can be deleted and will be repopulated/rebuilt after the next boot.

That is: do not delete /private/var/folders/ itself!

But below that, you may trash anything and then reboot. 

Note that a few files will be in use or protected, so you could only delete them via the Trash after a reboot.

In this case: make sure Chrome is closed, then trash only the big file you found and delete the file. Leave the rest as is.