Kotlin: Why are most variables underlined in Android Studio and how do I turn that off?

I wanted to know why most variables in Kotlin are underlined. Some files contain a lot of underlining which is very annoying. If I hover my mouse over a variable it doesn't give any information most of the time. But on some it says "This property has a backing field" or "Value captured in a closure". Does anybody know how to disable those underlines? Here is a screenshot with what I mean:

And realm is then underlined throughout the entire file.

It's just Editor Preferences.

Edit:

This is moved to

Preferences -> Editor -> Color Scheme -> Kotlin -> Properties and Variables

Thanks rmirabelle for the comment

For the old plugin, you can go to

Preferences -> Editor -> Color Scheme -> Kotlin

Then find Var (mutable variable, parameter or property) and remove Underscored effect.

I guess they just try to discourage using var by adding the annoying underscored. :P

In Android Studio 3.1.2 this has been moved to -

Settings > Editor > Color Scheme > Kotlin