There are only 2 "root-related" file - /system/xbin/su and /system/xbin/busybox. The phone's not rooted (since apps can't get root without SuperSu. but if you want to remove su, you can probably use the terminal app, run su, then rm /system/xbin/busybox and rm /system/xbin/su. Then you can uninstall the terminal app if you want.
Or just leave it alone. The files are small, about 2MB total.