Question

I need to remove a control (a textbox) from my page when a certain condition is verified.
Is it possible to do from code-behind or I need to use JavaScript.

NOTE I need to remove the control, not to hide…

Answer 1

Use Controls.Remove or Controls.RemoveAt on the parent ControlCollection.

For example, if you want to remove all TextBoxes from the page’s top:

var allTextBoxes = Page.Controls.OfType<TextBox>().ToList();
foreach(TextBox txt in allTextBoxes)
    Page.Controls.Remove(txt);

_{(note that you need to add using System.Linq for Enumerable.OfType)}

or if you want to remove a TextBox with a given ID:

TextBox textBox1 = (TextBox)Page.FindControl("TextBox1"); // note that this doesn't work when you use MasterPages
if(textBox1 != null)
    Page.Controls.Remove(textBox1);

If you just want to hide it (and remove it from clientside completely), you can also make it invisible:

textBox1.Visible = false;