Remove an item from a LINQ collection

I think I am putting my question correctly 🙂

I am querying the database using LINQ to retrieve some data. Please find the code below.

var leadtasktype = _context.LeadTypeTaskTypes.Where(l => l.LeadTypeId == item.Value);

foreach(LeadTypeTaskType l in leadtasktype){
    if (l.TaskTypeId == 21)
        //I need to remove an item which has the tasktype id 21

As I mentioned in the comments, I need to remove items from the leadtasktype based on my if condition. How do I do this?