To delete a string from a string list, call the list's Delete method, passing the index of the string you want to delete. If you don't know the index of the string you want to delete, use the IndexOf method to locate it. To delete all the strings in a string list, use the Clear method. 

The following example uses IndexOf and Delete to find and delete a string:

with ListBox1.Items do
  begin
    FoundIndex := IndexOf('bureaucracy');
    if FoundIndex > -1 then
      Delete(FoundIndex);
  end;

int BIndex = ListBox1->Items->IndexOf("bureaucracy");
if (BIndex > -1)
  ListBox1->Items->Delete(BIndex);