Possible to turn of wireless function, but keep Ethernet function?

I do not know. I apologize for you not understanding, I'll try to explain better. :) The Extender model is WN2500RP. I live with my family (I'm 17). And for some reason, the connection in my room is completely ****. I used to get a signal to my room, allowing me to use the wireless antennas on my computer to get a signal and innternet. After a while, it got slower and slower and in the end, it stopped. So I had to live without internet on my desktop computer for 6 months or more. I even formatted (Correct word? I reset to factory settings, if that is correct? Sorry.) my desktop, but that did not work. If I moved my computer downstairs, where our router is, it would work, but when I got back to my room it did not work anymore. Approx. 6 months ago, I bought a WiFi Extender (Model: WN2500RP) and all was well. Until the signal, allegedly, interferes (?) with out main router. I do not understand how it is possible, but my stepdad spoke to our ISP, and he had to change the password for the internet (so that I would not use my extender) and test his speed and stuff that our ISP told him to do. When he was done he told me the new password, I connected and got set up, and he messaged me when it was done and told me he could not use the AppleTV because of how slow it is. I'm now hoping there's a way to turn the WiFi function off, so that I can just use my Ethernet connection. What sucks about that is that I get **** speed on my phone and other devices in my room. Please answer, I greatly appreciate it.