Form1.cs

namespace StudentApp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        // Delete Button
        private void button3_Click(object sender, EventArgs e)
        {
            var userResponse = MessageBox.Show("Are you sure you want to delete?", "WARNING", MessageBoxButtons.YesNo, MessageBoxIcon.Warning);
            if (userResponse == DialogResult.Yes)
            {
                MessageBox.Show($"Student: {Data.students.ElementAt(studentGrid.CurrentRow.Index).Lname} has been removed!");// has to come before removal because it will show the index beneath it
                Data.students.RemoveAt(studentGrid.CurrentRow.Index);
                studentGrid.DataSource = null;
                studentGrid.DataSource = Data.students;// refresh
            }
        }

        private void studentGrid_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {

        }
        // When the form loads do this...
        private void Form1_Load(object sender, EventArgs e)
        {
            studentGrid.DataSource = Data.students;
        }

        private void btnRefresh_Click(object sender, EventArgs e)
        {
            studentGrid.DataSource = null;
            studentGrid.DataSource = Data.students;
        }

        private void btnAdd_Click(object sender, EventArgs e)
        {
            AddForm addForm = new AddForm();
            addForm.ShowDialog();
        }
    }
}