Please refer this article

Edit GridView using BoundField Column in ASP.Net

Add the LinkButton for deleting the records in above article GridView.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" OnRowEditing="OnRowEditing">
    <Columns>
        <asp:BoundField DataField="Name" HeaderText="Name" ItemStyle-Width="150" />
        <asp:BoundField DataField="Country" HeaderText="Country" ItemStyle-Width="150" />
        <asp:TemplateField>
            <ItemTemplate>
                <asp:LinkButton ID="LinkButton1" Text="Edit" runat="server" CommandName="Edit" />
                <asp:LinkButton ID="LinkButton4" Text="Delete" runat="server" OnClick="OnDelete" />
            </ItemTemplate>
            <EditItemTemplate>
                <asp:LinkButton ID="LinkButton2" Text="Update" runat="server" OnClick="OnUpdate" />
                <asp:LinkButton ID="LinkButton3" Text="Cancel" runat="server" OnClick="OnCancel" />
            </EditItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

LinkButton Onclick event for Deleting the Rows.

VB.Net

Protected Sub OnDelete(sender As Object, e As EventArgs)
    Dim row As GridViewRow = TryCast(TryCast(sender, LinkButton).NamingContainer, GridViewRow)

    Dim dt As DataTable = TryCast(ViewState("dt"), DataTable)
    dt.Rows.Remove(dt.Rows(row.RowIndex))
    ViewState("dt") = dt
    Me.BindGrid()
End Sub

C#

protected void OnDelete(object sender, EventArgs e)
{
    GridViewRow row = (sender as LinkButton).NamingContainer as GridViewRow;

    DataTable dt = ViewState["dt"] as DataTable;
    dt.Rows.Remove(dt.Rows[row.RowIndex]);
    ViewState["dt"] = dt;
    this.BindGrid();
}

For inserting the GridView Rows please refer this article

Using SqlBulkCopy to insert bulk data from GridView to database in ASP.Net

You can also use For loop to insert the GridView Rows in Database.

Refer:

1. Bulk Insert Data from GridView Rows into Database in ASP.Net