NSString *dataString = @"Substring removing";

dataString = [dataString stringByReplacingCharactersInRange:NSMakeRange(9,
                          9) withString:@""];
//dataString is "Substring"

dataString = [dataString stringByReplacingCharactersInRange:NSMakeRange(0,
                          3) withString:@""];
//dataString is "string"

NSMutableString *mutableString = [NSMutableString stringWithCapacity:9];
[mutableString appendString:@"Substring"];
[mutableString deleteCharactersInRange:NSMakeRange(0, 3)];
//mutableString is "string"