Sub Demo()
Application.ScreenUpdating = False
Dim CCtrl As ContentControl, i As Long
Dim Pwd As String, pState As Variant
With ActiveDocument
  If .ProtectionType <> wdNoProtection Then
    Pwd = InputBox("Please enter the Password", "Password")
    pState = .ProtectionType
    .Unprotect Pwd
  End If
  With .Range
    For i = .ContentControls.Count To 1 Step -1
      With .ContentControls(i)
        If .Type = wdContentControlCheckBox Then
          If .Checked = False Then
            With .Range.Rows(1)
              .Range.Delete
              .Delete
            End With
          End If
        End If
      End With
    Next
  End With
  If pState <> wdNoProtection Then .Protect Type:=pState, NoReset:=True, Password:=Pwd
End With
Application.ScreenUpdating = True
End Sub