How to release the object of xdocument

I am getting this error

The process cannot access the file 'G:\27thJune2016\OutClique.UI\XmlFiles\Blog.xml' because it is being used by another process.

here is my code..

XmlDocument XDOC = new XmlDocument();

XDOC.Load(System.Web.HttpContext.Current.Server.MapPath("~/XmlFiles/Blog.xml"));

XmlNode RootNode = XDOC.SelectSingleNode("//Blogs");

XmlNode childnode = XDOC.SelectSingleNode("/Blogs/IDs");

//check whether childnode exist or not.

if (childnode != null)

childnode.ParentNode.RemoveChild(childnode);

XmlElement XEle = XDOC.CreateElement("IDs");

XEle.SetAttribute("id", Convert.ToString(ID));

RootNode.AppendChild(XEle);

XDOC.Save(System.Web.HttpContext.Current.Server.MapPath("~/XmlFiles/Blog.xml"));(in this line i am facing the ;problem)