If you know what you are doing, this should be an half an hour job maximum. I have a discontinued product plugin with woocommerce. Take a look here: [url removed, login to view]
It works well, however, it will still show add to cart on main page with product listings and that its in stock. Need to have the "Add To Cart" button say View Item and the "in stock" section to say discontinued
Running Woocommerce: Version 3.3.4
Wordpress Version: Version 4.9.4
10 freelancers are bidding on average $31 for this job
That's for now. Once I have reviewed the plugin code I'll get back to you. It may be to do with your theme and not the plugin though. We'll see. Kind Regards, Dobri
WooCommerce customization expert. I can have this done for you today and you will be very happy with the turnaround time and professionalism. Shoot me a message so I can get to work for you.