How to permanently disable http_proxy

When I remove proxy from System/Network and apply it system wide it still remains when working in console. When I run:

env | grep proxy

it prints:

http_proxy=http://proxy.studnet.lan:8080
ftp_proxy=ftp://proxy.studnet.lan:8080
socks_proxy=socks://proxy.studnet.lan:8080
https_proxy=https://proxy.studnet.lan:8080

I could remove it with:

unset http_proxy
unset ftp_proxy
unset socks_proxy
unset https_proxy

but it's not permanent, when I reopen terminal these proxy variables are again setted.

How to remove them permanently?