How to Remove the Flash Drive From a MacBook
USB flash drives, which connect to computers through the USB port, store computer files. A MacBook computer has two USB ports on the left side of the computer. You should not remove a flash drive by pulling it from the connection point without ejecting it first. If the MacBook is using the drive when you remove it, the drive could be damaged. Additionally, the Mac performs some basic maintenance on the drive before signaling you can remove it, according to the website My First Mac.
Click on the "Desktop" icon in the Finder.
Click on the icon of the flash drive and hold the trackpad button down as you drag the icon to the Trash folder in the Dock. The Dock is located along the bottom of the MacBook screen by default, but it can also be on the right or left side.
Drop the flash drive icon on the Trash folder to unmount it from the Desktop.
Remove the flash drive from the USB port of the MacBook.