Chip Pearson says that he actually "fixed" his keyboard by taking that key off.
Others say that they left the key, but removed the spring underneath.

But you could use a couple of macros (one to disable and one to enable):

Option Explicit
Sub disableF1()
Application.OnKey "{f1}", ""
End Sub

This would toggle it back to normal.

Sub enableF1()
Application.OnKey "{f1}"
End Sub

If you're new to macros, you may want to read David McRitchie's intro at:
http://www.mvps.org/dmcritchie/excel/getstarted.htm

sonic_d_hog wrote:

I use the <F2 key constantly to enter the edit mode and sometimes I
accidentally hit the <F1 instead, starting Excel's help feature. Can I make
it stop?

--

Dave Peterson