How does asp.net remove HTML tags?

Today, I was suddenly asked to read data from the database sometimes with HTML tags, and if the data is packed in a container such as TextBox, the tags will be output as strings, this is definitely not your own effect, so how to remove these HTML tags!
[Csharp]
Protected void button#click (object sender, EventArgs e)
{
String str = ConfigurationManager. ConnectionStrings ["sqlstr"]. ConnectionString;
Using (SqlConnection sqlcon = new SqlConnection (str ))
{
Using (SqlCommand sqlcom = sqlcon. CreateCommand ())
{
Sqlcom. CommandText = "select * from T_Blog where Uname = 'Mary '";
Sqlcon. Open ();
SqlDataReader reader = sqlcom. ExecuteReader ();
If (reader. Read ())
{
 
String content = reader ["Bcontent"]. ToString ();
// Declare an immutable Regular Expression
[Csharp]
Regex regex = new Regex ("<. +?> ");
Content = regex. Replace (content ,"");
This. TextBox1.Text = content;
}
}
}
}

The regular "<. +?>"

 

From Yang Fei's column