DOPO DPW8A-BT - Forgot Password Help

Hi,

I forgot the password of my DOPO DPW8A-BT windows tablet. When I tried to 'reset the PC', it states 'additional free space is needed on the drive where Windows is installed. Free up some space and try again.' But of course I can't because I can't get in there to free space! I am not able to boot using bootable USB stick as well, because there is no boot sequence available in UEFI firmware settings. My USB Stick is not even recognized in Use a Device option in Advanced Options which comes after restarting the system while pressing shift from login screen. Request your help in this matter and let me know what else can I do to resolve this issue. Looking forward for your help.

Regards

Yasir