Another beginner Q

I remember seeing a button on the A320 flight deck for disconnection of
the nosewheel steering control. I also remember the cap'n saying that
that's used during the push-back of the aircraft. He mentioned some
reason for that but I don't recall what; possibly something to do with
the hydraulics not getting accidentally triggered off or something like
that.

Can someone get me up to speed on this?
Cheers,

Ramapriya