If you want to start up again from the disk you erased, select Reinstall macOS in the utilities window, then click Continue and follow the onscreen instructions to reinstall macOS.Quit Disk Utility to return to the utilities window.
If you don't see this button, click Erase instead. The Split Strokes mode only acts on annotations created with pen or marker tools, and will only erase those parts of the strokes directly below the.