How to hide Scroll bar of textarea

i have a Textarea as following code.

 <textarea rows="3" cols="3" Label="Plan Comments" TextMode="MultiLine" runat="server" ID="txtPlanComments"
                       style="height:50px;width:100%;overflow-x: hidden; overflow-y: scroll;" MaxLength="2000"

SubType="FREEFORM">
                       </textarea>

i want to hide it's scrollbar through java script as per my requirement.

i am doing this

var txtPlanComments = _getObject("<%=this.txtPlanComments.ClientID.ToString() %>", true);
 txtPlanComments.overflow='hidden';
 
//txtPlanComments.style.overflow = &q ...