Hello Hammad,
and welcome to the community! 

It should be possible to set it in the markup using TextAlignment="Right" like: 

<ignav:UltraWebTree ID="UltraWebTree1" runat="server"
                    TextAlignment="Right"
                    Cursor="Hand"
                    DataSourceID="OrgSiteMapDataSource1"
                    Indentation="20"
                    Width="170px"
                    WebTreeTarget="HierarchicalTree"
                    BorderColor="#E0E0E0"
                    ImageDirectory="~/Images/">
    <selectednodestyle backcolor="Green" borderstyle="None" />
    <images>
    </images>
</ignav:UltraWebTree> 

Additional Info:
You could reference to the official online documentation.

TextAlignment - Enumeration for control of text alignment. The available options are Center, Left and Right.
All available NodeClassMembers are listed here.

 Please let me know how this works for you!