Removing Substring in asp.net with c#

You are using Substring method wrongly. Here we go:

Substring has two overloads :
Overload 1: Substring(int Starteindex) - It will take the start index and will return all the characters after the start index
e.g.

class Program
{
    static void Main()
    {
	string input = "Angel Nursery School; 001";
	string sub = input.Substring(6);
	Console.WriteLine("Substring: {0}", sub);
    }
}

It will return : Nursery School; 001

Overload 2: Substring(int Starteindex, int Endindex) - It will return all the characters between startindex and Endindex
e.g.

class Program
{
    static void Main()
    {
	string input = "Angel Nursery School; 001";
	string sub = input.Substring(6, 13);
	Console.WriteLine("Substring: {0}", sub);
    }
}

It will return : Nursery

Now coming back to your case. If you want to remove 001, then modify your code as :

String text = ddlschoolname.Text;
String numbers = text;
if (text.Length >= 10)
{
    numbers = text.Substring(0, text.Length - 3);
}

Hope this helps.
All the best.

You can do it in 2 ways.

using substring

to use this you need to know how many digits are there
here for your example you can use this
here you need to remove last 4 characters thats why i gave length-4
in place of 4 you need to replace the number according to your requirement.

If space is there between ; and 001 then use length-5

text.substring(0,text.length-4);

if every string contains ; then you can split as below

string[] str=text.split(';')
//In str[0] you will get school name.

Hope this helps you