There are several functions in Rocket League that I have no use for. I reconfigured my controller layout quite a lot, and put things I didn't want to use (like the Push-to-Talk button for example) on the left thumbstick click. During the pressure of a match, I often click the thumbstick by mistake and activate a whole host of functions that I don't want. However, I can't find a way to unbind the functions. I would like to have it that certain functions are covered by the keyboard only, and unbound from the controller. Is there a way to do this?
As you've not specified, I'm assuming you're on PC with an XBox-style controller because you're using a keyboard.
Most keybindings can be removed by pressing Y if you are using the gamepad in the menu, or by clicking the cross on the right hand side of the row for that keybinding if you are using the mouse. Once a keybinding is cleared, you can set a new one for the keyboard only. Some of the defaults are set this way.
You can also disable voice chat completely in the audio tab which will override the push to talk controls, but then you will not be able to hear other players either.