can't change apt-get proxy...

[saif32]

Hi guys, i use kubuntu 12.04, i once setting the apt proxy in tetminal with this command :

kdesudo kate /etc/apt/apt.conf.d/95proxies

then write :

Acquire::http:roxy "http://proxy.xx.ac.id:3128/";
Acquire::https:roxy "https://proxy.xx.ac.id:3128/";
Acquire::ftp:roxy "ftp://proxy.uny.xx.id:3128/";
Acquire::socks:roxy "socks://proxy.xx.ac.id:3128/";

to connect internet in my college's network.
when i try to connect with modem, i cant change the proxy even though i delete that file...
is anybody know how to fix it?