Cleaning up internal storage via PC

[AC Question]

Hello,
I want to clean up my phone's internal storage manually by connecting it to PC. When I connect the phone, Windows shows 4.3 GB free out of total 11.5 GB. That meas that about 7.2 GB is occupied. However, when I check the properties of the folders, it shows a total of only 1.3 GB in all folders. That means that probably Windows can't see most of the files on the phone's storage. "Show hidden/system files" option is checked in my Windows.
Is there a way I can see all files on the phone's internal storage?
I guess, the phone model does not matter for this question, but just in a case it is Sony Xperia Z3 Compact.

 

[Tim1954]

I would be really reticent to try that. If you delete some code you will brick the device.. Tread carefully here unless you're really good with programming.