NEED MORE SPACE ON WINDOWS 8.1 TABLET!!!!

I have a Windows 8.1 Nextbook 8 inch tablet;
• 8 inch High-resolution 1280 x 800 Touch Screen (Twisted Nematic Liquid Crystal Display)
• Intel® ATOM™ Quad-Core Z3735G Processor / 1.8GHZ (2M Cache, up to 1.83 GHz)
• 1GB DDR3L; 16GB onboard storage
• WIFI 802.11 b/g/n
• Bluetooth4.0
• Front Camera 0.3 MP ; Back camera 2.0 MP
• Micro HDMI
• Micro-SD card slot for expansion to 64GB
• Support 3 -axis G-sensor
• Built-in Headphone/Microphone
• Charging indicator light

I know the specs and the tablet itself isn't the greatest hardware wise, but it's good for surfing the web, playing games, and small apps. What I'm mad about is the the tablet said it comes with 16GB of space and a 16GB micro sd card. The SD card works, but the tablet only came with 2GB not even enough for big apps and Microsoft Office they promised. I know Windows stopped moving apps to the SD card and I have tried various software to attempt to get space the built in disk cleaner which is windows disk cleaner only gave 7mb (FAIL) and I tried Wise Disk Cleaner which gave me 1.88GB I was satisfied, but I want as much space as I can get any software I can use or what I could do to get space I can't delete the recovery file because, no USB 2.0 port. P.S. I deleted unimportant apps and the app with the most space is only 80 mb I only have like 10 apps and only 1.28 GB of space I haven't downloaded anything since. I DO NOT WANT TO BUY OR UPGRADE THE DISKS'!!!