need advice on a winbook 8" tablet I have an issue with

yellow1053

I picked up an 8" used winbook tablet from someone, from what I can tell, it has a 15 gig hard drive, but it says the C:/windows drive is only 9.6 gigs, and it is entirely full. I went through each folder one at a time and checked properties, and the two folders that have 2 gigs used and 7 gigs used are "windows" and "winsxs" respectively. Google says it needs the winsxs folder to run windows, so there is literally nothing I can delete. it keeps telling me the hard drive is full, and I tried disk cleanup, and compress files, neither of which helped. it is running windows 8.1 and has 1 gig of ram installed. I realize I can plug in an external HDD, or put in a micro SD card, but shouldn't there be a little free space onboard?? There is only four programs installed when I go to the programs section of the control panel. two of which are to an expired anti-virus program, but when I try to uninstall them, it errors out. (possibly due to no space) Any thoughts?

Thanks.

PowerSpec_KenJ

You can try opening an elevated command prompt (run as admin) and run the command: dism /online /cleanup-image /startcomponentcleanup /resetbase. That should clear out much of the winsxs folder and it should clean up unnecessary windows update files that disk cleanup will not touch. This command works well if it will run, but it may fail due to the lack of free space. The other option would be to reinstall Windows. If this doesn't work, you may need to run Windows reset. It should allow you to install an SD card to cache files. Here are some instructions from Microsoft:

Recovery options in Windows - Microsoft Support