Yes... but good luck getting it done properly without the usual call centre staff. Might be do-able with the website.
You have to cancel the outbound, pay the penalty and add another leg somewhere (doesn't have to be HNL) so that the value of the balance of your ticket has a open segement to use in the future, for one more penalty. You might have to pay an adcol if you get a bad agent you can't find a matching fare basis $ wise. Meaning, for example, you can't put in an L fare for less $ when you are already booked in H. If you do that the system will exchange you down to the lower fare and you will be out $. If you don't care about your outbound segs value, then just pay the penalty to change.
Good luck.... u will need it