how to remove char from string code example

Example 1: java string remove character

String str = "abcdDCBA123";
String strNew = str.replace("a", ""); // strNew is 'bcdDCBA123'

Example 2: remove charachter from string

StringBuilder sb = new StringBuilder(inputString);

Example 3: remove charachter from string

if(String.charAt(1) == String.charAt(2){
   //I want to remove the individual character at index 2. 
}