The icon you have at your launcher is an installer, so, you probably downloaded it, asked it to install busybox and did the full root. You can safely remove that app, by doing that you're removing the installer only, busybox binary (which is needed by most of the root apps) will stay installed...
Sony Xperia M dual [C2004]
ROM: 15.5.A.1.5 (stock)
Android version: 4.3 (rooted)
Bootloader: locked (unlockable)