Remove an observer in Ember component

I want to remove a observer I registered at a current point. Say I got following component:

export default Ember.Component.extend({
    observeSomeProp: function() {
        //do something 
    }.observes('someProp'),

    obserOtherProp: function() {
       if( condition ) {
           //remove observeSomeProp
       }
    }.observes('otherProp')  
});

I am reading the docs, the removeObserver function needs three arguments 'key', 'target' and 'method'. I suppose the 'method' argument would be observeSomeProp for given example, but what about the 'key' and 'target'?