//first i am filling listview control.
 private void Form1_Load(object sender, EventArgs e)
    {
        FirebirdEntity asa = new FirebirdEntity();

        ObjectQuery<NEW_TABLE> sorgu = asa.NEW_TABLE;

        foreach (var item in sorgu)
        {
            ListViewItem list = new ListViewItem();
            list.Text = item.AD;
            list.SubItems.Add(item.SOYAD);
            list.Tag = item;
            listView1.Items.Add(list);

        }
//than getting New_table entity from listview's tag property.
 private void button3_Click(object sender, EventArgs e)
    {

            using (FirebirdEntity arama = new FirebirdEntity())
            {

               NEW_TABLE del = (NEW_TABLE)listView1.SelectedItems[0].Tag;
               arama.DeleteObject(del);
               arama.SaveChanges();


            }}

NEW_TABLE del = (NEW_TABLE)listView1.SelectedItems[0].Tag;
arama.Attach(del);
arama.DeleteObject(del);
arama.SaveChanges();

private void Form1_Load(object sender, EventArgs e) {
    FirebirdEntity asa = new FirebirdEntity();

    ObjectQuery<NEW_TABLE> sorgu = asa.NEW_TABLE;
    foreach (var item in sorgu) {
        asa.Detach(item);
        // add to listView1
    }
}

public void DeleteSharedDoc(SharedDocs shareddoc)
{
       this.ObjectContext.SharedDocs.DeleteObject(shareddoc);
}

public void DeleteSharedDoc(SharedDocs shareddoc)
{
var query = (from w in this.ObjectContext.SharedDocs
            where w.UserShareName == shareddoc.UserShareName
            && w.UserShareUsersEmail == shareddoc.UserShareUsersEmail
            && w.DocumentId == shareddoc.DocumentId
            select w).First();
this.ObjectContext.SharedDocs.DeleteObject(query);
}

int id = convert.toint32(some text field from the page);
entity data = new entity();
var del = (from record in data.records
          where record.id == id
          select record).FirstOrDefault();
data.deleteObject(del);
data.saveChanges();

CREATE TABLE [dbo].[Department]
    (
          DepartmentUUID [UNIQUEIDENTIFIER] NOT NULL
        , DepartmentName varchar(24) not null
        , CreateDate smalldatetime not null
    )
GO


ALTER TABLE [dbo].[Department] ADD CONSTRAINT PK_Department PRIMARY KEY NONCLUSTERED (DepartmentUUID)
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT CK_DepartmentName_Unique UNIQUE (DepartmentName)
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT [DF_Department_DepartmentUUID] DEFAULT ( NEWSEQUENTIALID() ) FOR DepartmentUUID
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT [DF_Department_CreateDate] DEFAULT ( CURRENT_TIMESTAMP ) FOR CreateDate
GO

public int DeleteDepartment(Guid departmentUUID)
{

    int returnValue = 0;

    Department holder = new Department();
    holder.DepartmentUUID = departmentUUID; // DepartmentUUID is the primary key of this object (entity in the db)

    using (MyContectObject context = new MyContectObject())
    {
        context.AttachTo("Departments", holder);

        context.DeleteObject(holder);

        int numOfObjectsAffected = context.SaveChanges();
        returnValue = numOfObjectsAffected;

        context.Dispose();
    }

    return returnValue;

}