AIrport Extreem was in my network and I rplaced it hooked it up to my mac so how do i get to see it - disable the WIFI - and use it for backups.

Sorry, this does not tell us whether you have an AirPort Extreme with an attached 4 TB drive, or whether you are saying that you have a Time Capsule with a built in 4 TB drive. Apple did not offer a product with a 4 TB drive built in though, the maximum size of the drive inside a Time Capsule was 3 TB.

Can you tell us please whether you have an AirPort Extreme or an AirPort Time Capsule?

If you do not know what product that you have, you can connect to the WiFi provided by the Apple product and then use AirPort Utility to determine what model of AirPort router you have.

Open AirPort Utility on your Mac (Finder > Applications > Utilities > AirPort Utility)

Hold down the option key on your Mac while you double-click on the picture of the AirPort

The Model will appear at the top of the window

In the example below, you can see that I have an AirPort Time Capsule. What product appears next to Model when you use the steps above to identify the product that you have?

The AirPort Extreme does not have a built in hard drive, so it could not be used for backups unless you are saying that you have attached a separate USB hard drive to the USB port on the AirPort Extreme.

Or, perhaps you really meant to say that you have a Time Capsule.......which is an Apple router with a built in hard drive that was designed to handle backups using Time Machine on your Mac.

Can you clarify what product that you have......an AirPort Extreme.....or a Time Capsule?

Either way, if you want to use the product for backups, you would NOT connect it to your Mac......you would first reset the device and then connect it to your new WiFi 5 router using a wired Ethernet cable connection. Once that is accomplished, you will be able to back up over the WiFi 5 router's wireless network.......or......you would also have the option of connecting your Mac directly to the backup device.

So let's first get a clear understanding of what Apple product that you have......then......we can proceed with setup instructions.

That is good news for your AirPort Extreme or your AirPort Time Capsule......whichever product that you have. If you have an AirPort Time Capsule, it does not have a 4 TB drive unless you replaced the 2 TB or 3 TB drive in the product that Apple offered.