无法从数据库中删除数据

Question

我一直在研究可以从sql数据库中删除用户的表。我几乎改变了所有内容，无法正常工作。

Private Sub ButtonDelete_Click(sender As Object, e As EventArgs) Handles ButtonDelete.Click
    Try
            If MessageBox.Show("Do you really want to delete this User?", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Warning) = DialogResult.Yes Then
                connection = New SqlConnection(My.Settings.ConString)
                Dim command As New SqlCommand("Delete from Operator where User = @User")
                command.Parameters.Add("@User", SqlDbType.NVarChar).Value = DataGridView1.SelectedRows(0).Cells(0).FormattedValue
                command.Connection = connection
                ds.Clear()
                connection.Open()
                command.ExecuteNonQuery()
                connection.Close()
            Else
                MessageBox.Show("Operation Canceled")
                Exit Sub
            End If
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        Try
            connection.Open()
            Dim str As String
            str = "Select * from Operator"
            adapter = New SqlDataAdapter(str, connection)
            adapter.Fill(ds)
            DataGridView1.DataSource = ds.Tables(0)
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Try