You can choose whether to have the check box unchecked when you run the macro.e.g.
Code:
Sub ClearForm()
Dim oCC As ContentControl
If ActiveDocument.ProtectionType <> wdNoProtection Then
ActiveDocument.Unprotect
End If
For Each oCC In ActiveDocument.ContentControls
On Error Resume Next
oCC.Range.Editors.Item(1).Delete
On Error GoTo 0
Select Case oCC.Type
Case Is = wdContentControlDropdownList
oCC.Type = wdContentControlText
oCC.Range.Text = ""
oCC.Type = wdContentControlDropdownList
Case Is = wdContentControlCheckBox
oCC.Checked = False
Case Else
oCC.Range.Text = ""
End Select
oCC.Range.Editors.Add (wdEditorEveryone)
Next oCC
ActiveDocument.Protect wdAllowOnlyReading
End Sub