Button Remove c # form button

Hi, I want to make the selected rows be eliminated so you look at the interface

This is the code I have but it is not

 private void BtnQuitar_Click(object sender, EventArgs e)
    {
        if (DataGridViewSelectionArea.SelectedRows == null)
        {
            MessageBox.Show("Debes seleccionar una fila del grid");
            return;
        }
        var dt = (DataTable)DataGridViewSelectionArea.DataSource;
        foreach (DataGridViewRow item in DataGridViewSelectionArea.SelectedRows)
        {
            var row = dt.AsEnumerable().FirstOrDefault(r => r["Id"] == item.Cells["Id"].Value);
            if (row != null)
            {
                dt.Rows.Remove(row);
            }
            DataGridViewSelectionArea.DataSource = dt;
        }

But it does not fulfill its function, at the moment of using the button it sends me the messagebox of "you must select a row" and when I try to select the checkbox it does not let me do it, it remains as it is impossible to palom it, I just want to remove the row of selected checkboxes when clicking the remove button

This is the DataGridViewSelectionArea code:

  this.DataGridViewSelectionArea.dataGridView.Location = new System.Drawing.Point(550, 250);
    this.DataGridViewSelectionArea.dataGridView.Name = "DataGridViewSelectionArea";
    this.DataGridViewSelectionArea.dataGridView.Size = new System.Drawing.Size(250, 230);

    this.Controls.Add(this.DataGridViewSectionArea.dataGridView);

Every time I want to remove a row, it launches the MessageBox of "You must select a row of the grid" and I want the selected checkbox rows to be deleted from beforehand, thanks.