The subtract feature can be used to remove an object from a polygon that it does not belong to.
To subtract one polygon from another, select the polygon that you would like to remove, click Subtract or hold down Shift + S, and select the polygon that you would like to cut it from. This will create a perfect border between the original polygon and the new one.
The brush tool
Merge and Subtract are currently supported on images. Check out this article for instructions on how to add and subtract polygons in images and video using the brush tool.
Updated about a month ago