Question [Q] Delete whole ROM

Hi all,

I am new to android development but I have some issue regarding my China's Tablet (Aigopad M80e).

I have rooted the tablet by searching around internet and after i root, I found that I could not install any application.
I found my Storage become 0.0kb so that i couldn't even able to do anything even I uninstall the existing apps, the storage is still the same.
Some internet guide said about xbin or download root File explorer to delete particular file but I couldn't able to install it at all.
Any way to delete whole ROMs? or any other solution? It's really had me so much.
Appreciate so much.