It is not possible to have the AirPort Extreme connect to your existing modem over wireless, if that is what you are asking. The connection between the AirPort Extreme and modem must be wired. The best and most reliable way to do this is using an Ethernet cable.
If you cannot run the Ethernet cable, then a pair of Ethernet Over Powerline (EOP) adapters might be able to send the signal over the existing AC powerlines in your home.
The theory with these devices is that you already have the wiring in place, you just need the adapters. In practice, things do not always work as well as the theory might suggest. After all, you are trying to send a very low voltage signal over high voltage lines....quite a challenge.
So, if you decide to try a pair of EOP adapters (I'm not recommending that you do, simply pointing out that they might be an option), it would be wise to make sure that you understand the store's return policy in advance, before you buy.
The bottom line is that you will not know how well......or even if......the EOP adapters will work in your home until you try them out in your home, since every home installation is different.
Any computer / electronics superstore will have a selection of EOP adapters, sometimes called HomePlug adapters, on hand. Ask the salesperson what they would recommend for your installation. Good luck!
"Is there a way to/how do I wipe it?"
Sorry, I'm afraid that I don't understand what you are asking here. If you are asking about erasing the current network settings that might be in place on the AirPort Extreme, a Hard Reset will do this. Please refer to this subject in the Setup Guide.