$raw_value = '["0","1","3"]';

$array_value = json_decode($raw_value);

if(!is_array($array_value)) $array_value = array();

	

// Add Value

$value_to_add = '2';

if(!in_array($value_to_add, $array_value))  // if is not already available in array

	array_push($array_value,$value_to_add);



// Remove Value

$value_to_remove = '0';

if(in_array($value_to_remove, $array_value)) // if value to remove is available in array

	$array_value=array_diff($array_value, array($value_to_remove));



$new_raw_value = json_encode($array_value);