how do I 'forget' a wifi network

[Uabcar]

For some reason I'm getting prompted to join my companies wifi network each time I open Safari. I get the apple id/password login screen. I just want to use 3G as I always have.

I thought there was a 'forget this network' button somewhere- but can't find it for the life of me. I have 'Ask to Join Networks' turned off.

Thanks

 

[Patriot24]

Settings > Wi-Fi > Arrow button next to network name > Forget this Network