Removing usb drive

I have created a medical history file on a usb drive plugged in to the back of my iMac. How do i remove the drive without without causing problems such as loss of date. There was no option to "close file," there is an option to "eject" the disc. Is this the way to remove such a drive from the iMac? Any help greatly appreciated.

Right click on the disk image then select eject is the easiest way

Eject Disk is what you want to do. Make sure you don't have any apps accessing files on the disk. If so you will get a warning message stating the disk cannot be ejected until you close the files or quit the app. After ejecting the disk you can remove it when the icon disappears off the desktop.

You can also drag the USB drives icon to the trash. You will see the trash turn into an Eject symbol. The Right Click way does the same thing

Ejecting disc

Thanks to you all for the assistance. I can't thank you enough.