To transfer via USB, connect the phone's USB cable to the PC. To transfer files to/from the pc, browse to the new USB virtual drive, find the files/folders and copy/paste away!
You can also try Android file transfer tool to transfer data to computer.

Android cleaner is a second option for bulk deletion or clearing. For cache, download it and install and run it on your computer, just one click to clear all phone caches and junk files.