remove a config path

Hello I want to code a plugin for Minecraft and I have a problem.
I want to remove in the config a path without using: this.getconfig.set("path", null).
I don´t want to use null.

 

If I use null there is no way to query whether it is null I believe.

And if I want to read from the config a string and then check to see if it is null, then it still gives me a nullpointerexception.

 

but if I use null then in the config its look like:
path: {}

 

I have:
this.getConfig.addDefault(path1.path2, null);
if (this.getConfig.getString(path1.path2) != null) { //here is the nullpointerexception
blablabla
}

 

oh, now ist work.
I have changed a little bit of the code and now it works

thx