Q: how to launch mac disk utility to help on partition usb?
A: launcher / others / disk utility can find GUI disk util 

Q: find info about "going-to-be-formatted-usb" info
A: $diskutil list --> /dev/disk2

Q: erase all disk
A: 
 disk_util / click on disk (not any vol) / erase
 	name: this is volume name (disk2_vol)
	format: ntfs (note: if use APFS then windows system cannot read it)
	arch: GUID

Q: after erase disk then what?
A: it will create a BIG partition table for this disk
 $ diskutil eraseDisk JHFS+ disk2_vol disk2 #Formatting disk2s2 as Mac OS Extended (Journaled) with name disk2_vol
 # look like this erase will create a JHFS+ file system for disk
 # if you more partition, then + one (note: it will always cut a slice from this BIG partition)