-Ok, so you dont have to format all drives, you will need to format just C, or the drive where you want to install Windows.
-You could overwrite current os with a new one but I dont recommend it because you are using SSD and it will take more space on SSD because of old files (windows.old).
-So how do you create a bootable Windows 10 USB ?, follow these steps:
1) Download windows 10 ISO (https://www.microsoft.com/en-us/software-download/windows10)
2) Scroll down a bit and find button "Download tool now"
3) Plug in your USB device, after you downloaded this tool and accepted EULA, click "Create installation media for another PC"
4) Choose which architecture you want (64bit), Choose wich version of Windows 10 you want to download and Language
5) Then choose recommended settings if you want, and choose "USB flash drive" it has to be more than 4GB
6) Click just next and download will begin
7) When you are done downloading and when it says "Your USB flash drive is ready" restart your PC, go to the BIOS/UEFI and go to boot section where you will select boot from USB flash drive, press F10 for save & exit and it should boot form USB.