how to delete character in string java code example

Example 1: how to delete character in string java

# subString(int start, int end);

String a = "Hello!";
b = a.subString(0,a.length()-1) #Remove the last String
# b should be "Hello" then

Example 2: remove charachter from string

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