Thanks for reaching out to us!
Normally the way the Erase button works within Clone is as a toggle: click it once and it turns blue (on) and the 2 sliders above it are “Eraser Size” and “Eraser Hardness”. Click it again and it turns grey (off) and the 2 sliders above it become “Brush Size” and “Brush Hardness”.
If you aren’t seeing this functionality, please try restarting Ribbet to see if that helps. Or, let us know if you have any further questions.
Regards – The Ribbet Team