Remove "Show Desktop" button next to the clock in Windows 7
Solution 1:
I really don't like those precompiled closed-source tools so here is a simple AutoIt script that you can copy in your startup folder:
$hwnd = WinGetHandle("[CLASS:Shell_TrayWnd]", "")
ControlHide($hwnd, "", "TrayShowDesktopButtonWClass1")
Solution 2:
7+ Taskbar Tweaker provides this option among many others. It's a robust little program that I've been using for quite some time without a problem. It adds exciting new functionality to the Windows 7 and Windows 8 taskbar and fixes some of its flaws.
