Configured the key. How is key cancel?

[demor140202]

  Hi Quarchodron, and other programmers.

I know how to configure the keys by clicking on which something will happen. But how do I cancel these settings? How do I make the key stop calling an action? 

Code:

            addEventHandler("onKey",function(key)
{
    if (key == KEY_7)
    {
setFreeze(true);
    }
})

I need "F7" to work as a freeze initially.
And then return " F7 " to its original form, so that the key does not start freezing.

All that happens is that I delete the "onKey" event . And in General, everything stops working (chat, list of players)