How To Eject a USB drive from a Chromebook

Select the Launcher icon in the lower left of the Chromebook screen and then select the Files icon to open file explorer.
In the left navigation menu, you will see your removable storage (like "SD Card" or "USB Device")
To safely remove the removable drive, click the Eject icon next to the removable drive's name. Once you do this, you'll see the device disappear from the left navigation menu.
You may now safely remove the device from your Chromebook.