Hello,
From my understanding, you are trying to find a way to undo an action in ROI.
Currently there is no shortcut to delete a recently drawn stroke in ROI. This issue is brought to the notice of our developers and it might be considered in the future releases of MATLAB.
As a workaround you can use the following,
- Place your cursor on any vertex of ROI, right click and select the option 'Delete Vertex'. This removes the vertex as well as the edges associated with the vertex
- Place your cursor on any part of the ROI other than the vertex, right click and select the option 'Delete Polygon'. This deletes the entire ROI on the image.