You want to minimize the application to system tray.
I do that for many programs that I have including Whatsapp.
You need to install a program that supports that feature.
I use "Actual Window minimizer".
It is not a free program. But you can find free programs that can have this feature.
You can do a search and you can try the free one in the below link that I did test on it last year and works fine.
I never tested it on Windows 10 but I was using it on Windows 8.
You can search for similar apps in the below link.