Since it’s hard to achieve local erasing function with LCD writing tablets, we look back to readitional magnetic writing board and found the fix.
The eraser is seprated from board back into a small brush-like part, becoming ‘big eraser’, relatively, ‘small eraser’ is at the other end of pen, both can erase partially the written.
Different from LCD writing tablets, magnetic ones have dark gray ink on white paper, closer to pencil writing on paper.