Nevermind i found the solution, You first disable the language branch in website languages. Then you go into version gadget in episerver UI and check "Show content in [language] only". 

Setting in admin (manage website languages) affects the visitors. To shut down editors from creating pages in certain languages you can set that on the site start page below tools and language settings.

My goal here was to disable a language-branch in edit mode and make it so that the content in the disabled branch can not be navigated to by visitors without deleting the language branch or unpublishing pages. 

If you have two languages in your "Website languages" disabling one language there does the trick. Editors are no longer able to create content or navigate to this language in the "Sites" tab in edit mode. And visitors are not able to navigate to the content in this language branch.

However if you use three languages the problem starts. Even if you disable one language in "Website languages" as long as there are two enabled languages you will still be able to navigate to the disabled language content as a visitor.

The only way to make sure that visitors are not able to navigate to the disabled language content is to go to the version gadget and check "Show content in [master language] only" which is a misleading title since if this is checked, the disabled language cannot be navigated to anymore, but any other secondary language is still available for visitors and editors.

My problem is fixed now but iam writing this down for anyone else that uses more then two languages and wants to freeze a language branch and its content :)