Deleting a trace when digitizing on an image in arcmap 10.2?

Question- How do i delete a trace i did mistakenly when am digitizing layers in arcmap?

Options for ArcMap 10.2
To delete while tracing, simply go to the icons on the menu bar and look for the undo button. Click on the 'undo' button and the trace will return to the last point before the mistake.
To delete the whole sketch, then stop and save edits, right click on the layer > open attribute table. locate the sketch on the attribute table, select it and delete.

Options for QGIS
In QGIS, you will have to delete the whole sketch by right clicking and select cancel in the entry box that pops up. secondly, you can right click the layer>open attribute table>select the sketch and click the bin icon to delete it.