public IActionResult LeaveActivity(int ActivityID) { int?userID = HttpContext.Session.GetInt32("userID"); if (userID == null) { TempData["error"] = "You need to be logged in to view this page"; return(RedirectToAction("Index")); } Participant leave = dbContext.Participants .Where(a => a.ActivityID == ActivityID) .FirstOrDefault(u => u.UserID == userID); dbContext.Remove(leave); dbContext.SaveChanges(); return(RedirectToAction("Dashboard")); }