Safely removing external HDD that system says is in use by another program

[popalong]

When I try to remove Drive F at the Computer window, or from the taskbar, it
says "can't remove, in use by another program".

This became an issue after I ran Windows Backup for the first time. Earlier
backup was the Acer version. Acer's version backs up C partition and
records on D. Windows backed up C and D and recorded on external drive F.

Here is the contents of Shared Folders

Share Name Folder Path Type # Client Connections Description
ADMIN$ C:\Windows Windows 0 Remote Admin
C$ C:\ Windows 0 Default share
D$ D:\ Windows 0 Default share
F$ F:\ Windows 0 Default share
IPC$ Windows 0 Remote IPC


How do I determine which program is preventing me from safely removing Drive
F?
Should I delete the Windows backup and use Acer's backup program
exclusively?
How do I delete the Windows backup?

 

[TheDuck]

One possible way is to look for windows backup process running in task
manager and end them. Otherwise shut the system down and then unplug the
drive and boot.

 

[popalong]

Thanks for answering. I was starting to think no one was going to see this.

I've thought about shutting down the system and disconnecting the external
hard drive as you suggested, but is there a downside to doing this when the
F drive is still registered in the system?

In task mgr. processes there's something called "BkupTray.exe" from an
outfit called "NewTech Infosystems". Don't know what it is. Do you?

Anyway, my virus scans have been running 3.5 hrs. I'll do the
shutdown-->disconnect-->reboot before the scheduled scan starts and see how
things look afterward.