delete in entity framework

You just call the SaveChanges afterwards:

var tag = from t in objLib.TagsField where t.Book_ID_FK == id select t;
        foreach (var t in tag)
        {
            objLib.TagsField.Context.DeleteObject(t);
        }
 objLib.SaveChanges();

Deleting with LINQ will bring all the rows you're deleting into memory. If they aren't in memory already, it will be faster to issue a SQL statement to delete the rows from the database.

Other than that, I would try Davids answer, since EF can bacth the updates together... I guess that also would improve perf some.

I used this to achieve the same thing...and I am using Entity Framework 5. I know the Using() block can be used now and is recommended - but here are the basic commands that work for me for just adding some alternatives:

/// <summary>
/// Method that will remove a favorite from the tblfavorite table.
/// </summary>
/// <param name="favoriteID"></param>
/// <returns></returns>
public Boolean DeleteFavoriteByFavoriteID(Int32 favoriteID)
{
    //Assume not found.
    IsFound = false;

    //Query the DB.
    var MatchedRec = (from f in dbContext.tblfavorites
                      where f.FavoriteID == favoriteID
                      select f).FirstOrDefault();

    //See if anything was found.
    if (MatchedRec != null)
    {
        IsFound = true;

        dbContext.tblfavorites.Remove(MatchedRec);
        dbContext.SaveChanges();
        return true;
    }

    //Default.
    return false;
}