Issue coding delete button to remove database entry from datagridview

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace JacobsPokedexMaster
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'pokedexDataSet.Cards' table. You can move, or remove it, as needed.
            this.cardsTableAdapter.Fill(this.pokedexDataSet.Cards);

        }

        private void searchByNameTextBox_TextChanged(object sender, EventArgs e)
        {
            BindingSource bs = new BindingSource();
            bs.DataSource = dataGridView1.DataSource;
            bs.Filter = "pokemon_name like '%" + searchByNameTextBox.Text + "%'";
            dataGridView1.DataSource = bs.DataSource;
        }

        private void addCardFormButton_Click(object sender, EventArgs e)
        {
            addCardForm AddCardForm = new addCardForm();
            AddCardForm.Show();
        }

        private void deleteCardButton_Click(object sender, EventArgs e)
        {
            string connectionString = null;
            string sql = null;
            connectionString = "Data Source=DESKTOP-NU2DVAO\\SQLEXPRESS;Initial Catalog=Pokedex;Integrated Security=True";
            sql = "DELETE from Cards WHERE pokemon_name = @pokemon_name";
            using (SqlConnection cnn = new SqlConnection(connectionString))
            {
                try
                {
                    cnn.Open();
                    using (SqlCommand cmd = new SqlCommand(sql, cnn))
                    {
                        cmd.Parameters.AddWithValue("@pokemon_name", SqlDbType.NVarChar).Value = dataGridView1.SelectedRows;

                        int rowsRemoved = cmd.ExecuteNonQuery();
                        if (rowsRemoved > 0)
                            MessageBox.Show("Card removed from Pokedex");
                        else
                            MessageBox.Show("Card not removed.");
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Error:" + ex.Message);
                }
            }
        }
    }
}