Yes, you can as long as the item is added to your invoice first.
If you don't have the declined item on your invoice, add it to your invoice.
Press the "X" icon on the task you wish to delete and mark as Declined (see image below). You can also select the Delete Icon from the Edit Invoice Item page.
Select the Add to Declined Work option (as seen below)
Once these steps have been completed, you can go to the Notes screen and select Suggested to see the notes