Totally remove all networks and start over, HOW???

I have a home network that is totally messed up over the years. I would like to wipe every thing out and start over from scratch. How do I do that? Do I need to do it on each computer, separately?

I want to wipe out all networks, both Ethernet and Wireless. Also totally remove any homegroup and start over with it too.

Here is what I will have when done:

Dishnet Satelite (Internet Provider)
Dishnet Modem

ASUS RT-N12 Router

Desktop Main Computer (Windows 8.1 - Ethernet)
Samsung Smart TV (Ethernet)
Dish Network Satellite TV (Links system to internet - Ethernet)

Laptop #1 (Windows 8.1 - Wireless)
Laptop #2 (Windows 7 - Wireless)
Laptop #3 (Windows 7 - Wireless)
Laptop #4 - Work (Windows 8.1 - Wireless)
Laptop #5 (used only as a internet uplink for a small program - Windows XP - Wireless)
Ipad #1 (Wireless)
IPhone #1 (Wireless)

All Computers (except Laptop #5) will be on a homegroup sharing files. Smart TV being limited to pictures only.

Laptop #4 is a work computer and needs to be seen (or at less accessed) ONLY by the main Desktop computer with only one certain user being able to access it.

Before I have had trouble limiting what is shared and what is not on different computers, especially limiting the work laptop files.

Please tell the steps needed to start over and then what is needed to get my system set up as I would like it to be...

Thanks,

DN1000