Add vertical scroll bar to panel

Panel has an AutoScroll property. Just set that property to True and the panel will automatically add a scroll bar when needed.

Try this instead for 'only' scrolling vertical.
(auto scroll needs to be false before it will accept changes)

mypanel.AutoScroll = false;
mypanel.HorizontalScroll.Enabled = false;
mypanel.HorizontalScroll.Visible = false;
mypanel.HorizontalScroll.Maximum = 0;
mypanel.AutoScroll = true;

Assuming you're using winforms, default panel components does not offer you a way to disable the horizontal scrolling components. A workaround of this is to disable the auto scrolling and add a scrollbar yourself:

ScrollBar vScrollBar1 = new VScrollBar();
vScrollBar1.Dock = DockStyle.Right;
vScrollBar1.Scroll += (sender, e) => { panel1.VerticalScroll.Value = vScrollBar1.Value; };
panel1.Controls.Add(vScrollBar1);

Detailed discussion here.