If you rightclick on an optionbutton within a group, you can choose
Format Control|Control Tab
There's an option for Cell Link.
You can assign a different cell for each group of option buttons.
This linked cell would tell you which option was selected: 1 through 5 in your
case.
If you set the linked cell to 0 (or just clear it), you can get rid of the
selected options.
But if you want a macro approach, you could run this:
Option Explicit
Sub testme()
ActiveSheet.OptionButtons.Value = xlOff
End Sub
It'll clear all the optionbuttons on the worksheet.
Maybe you could add a button from the forms toolbar with a nice "Click here to
clear all choices" caption.
Option Explicit
Sub testme()
Dim resp As Long
resp = MsgBox(prompt:="Are you sure?", Buttons:=vbYesNo)
If resp = vbYes Then
ActiveSheet.OptionButtons.Value = xlOff
End If
End Sub
That's a lot of buttons to clear without confirmation.