I am also interested in this. After leaving the starter area you have two minimaps (one of hem the "extended", but all options for it are greyed out). I have tried some settings in the configuration text files but does not seem to have any effect.

Did anyone find out how to disable the extended minimap? It's taking half of my 15.6 Inch screen

Hey Guys,

You can turn the extended map on and off by pressing N on the keyboard It is such a pain in the ass, i hate games that use those types of maps. Tera is horrible for it.
Hope this helps!

Thanks a lot! I was always looking in the UI Settings.