Issue in hiding Date part in DateTime Field

I have a requirement to add a field for preffered time to call customer.So i decided to create the datetime field and hide timeportion.

But its not working .I was using the below code,

function onloadHideDate()
{

debugger;
// Set the date
document.getElementById("ajec_datehidden").DataValue = new Date(2000, 1, 1);
// Hide the date part
document.getElementById("ajec_datehidden").childNodes.display ="none";//this is hiding time part
//document.getElementById("ajec_datehidden").childNodes[0].childNodes[0].style.display ="none";\\This is giving error
//document.getElementById("ajec_datehidden").childNodes[0].childNodes[1].style.display ="none";\\This is giving error
}