How do I unroot my (no name) Android tablet when nothing seems to work??

Hi forum
I bought a no name tablet when travelling in China a while back. Back at home (Sweden) I like to use it for tv, Netflix etc. but starting up e.g. the Canal Digital app, it says "App does not work on a rooted device".
Have tried SuperSU (says " Root undetected"), Universal Unroot (says "Please allow root access. If you cannot allow, the device is most likely not rooted") and a couple more.
What can I do??? Please advice, would feel like a real waste to throw away...
BR
PS. Looking in Settings, in simply says Model Number: K80, no manufacturer.