Create a startup disk
In this context a startup disk is a USB flash drive from which you can startup and. The capacity of the USB flash drive must be at least 2 GB. Any data on the USB flash drive will be lost when you create the startup disk.
It's assumed that you have downloaded an Ubuntu ISO image.
To create a startup disk from an Ubuntu ISO image:
Open Startup Disk Creator via the Activities search bar.
If the ISO image is in your Download folder and there is just one ISO image, Startup Disk Creator will have selected it, otherwise select the correct ISO image.
If your computer has just one USB flash drive, Startup Disk Creator will have selected it, otherwise select the correct drive.
Click Make Startup Disk.
Click Yes to confirm. The process should take ten minutes or less.
When the "Installation Complete" window opens click Quit.