How to delete image according to intial string of the images

Question

Hi friend,  i have one problem that in my project temp folder where i upload images according userid  so images is uploaded in temp folder in this manner userid_abc.jpg in this format 
so my problem is that how to delete that images according that userid  

using foreach loop how i collect images according to userid then matching that userid how i will delete images pleaz help me i very trouble to find out solution

i want to my  code in above format how can i do this pleaz help me
my code is global.asax.cs

protected void Session_End(object sender, EventArgs e) {

string userId = Session["UserId"].ToString();

string path;

string ImagePath =Session["Imagepath"].ToString();

path = System.Web.Hosting.HostingEnvironment.MapPath("~/temp/" + userId + "_" + ImagePath);

      FileInfo filepath = new FileInfo(path);

               if (filepath.Exists) {

File.Delete(filepath.FullName);

                Session.Abandon();

         

               }

       }