Here is some of sample code how you can check current user has admin rights

If Not PortalSecurity.IsPageAdmin() Then
Dim imgbtn As ImageButton = showeventdetails.FindControl("ImageButton1")
imgbtn.Visible = False
End If

If action.Visible And PortalSecurity.HasNecessaryPermission(action.Secure, PortalSettings, ModuleControl.ModuleContext.Configuration) Then

                                    If (ModuleControl.ModuleContext.EditMode = True AndAlso IsAdminControl() = False) OrElse _

                                            (action.Secure <> SecurityAccessLevel.Anonymous AndAlso _

                                             action.Secure <> SecurityAccessLevel.View) Then

                                        Dim ModuleActionLink As New LinkButton

                                        ModuleActionLink.Text = action.Title

                                        ModuleActionLink.CssClass = "CommandButton"

                                        ModuleActionLink.ID = "lnk" & action.ID.ToString

                                        AddHandler ModuleActionLink.Click, AddressOf LinkAction_Click

                                        Me.Controls.Add(ModuleActionLink)

                                        Dim Spacer As New LiteralControl(ItemSeparator)

                                        Me.Controls.Add(Spacer)

                                    End If