How can i decrypt this hash/salt helper function in c#

This the code used to encrypt for my password in mvc5 , How can i decrypt this ? can someone share your knowledge regarding this. thanks in advance

using System.Security.Cryptography;
using System.Text;
using System.Web;

namespace studentlog.Helper
{
    public class PasswordHelper
    {


        public static string ComputeHash(string plainText,
                                     string hashAlgorithm,
                                     byte[] saltBytes)
        {
            // If salt is not specified, generate it on the fly.
            if (saltBytes == null)
            {
                // Define min and max salt sizes.
                int minSaltSize = 4;
                int maxSaltSize = 8;

                // Generate a random number for the size of the salt.
                Random random = new Random();
                int saltSize = random.Next(minSaltSize, maxSaltSize);

                // Allocate a byte array, which will hold the salt.
                saltBytes = new byte[saltSize];

                // Initialize a random number generator.
                RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();

                // Fill the salt with cryptographically strong byte values.
                rng.GetNonZeroBytes(saltBytes);
            }

            // Convert plain text into a byte array.
            byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);

            // Allocate array, which will hold plain text and salt.
            byte[] plainTextWithSaltBytes =
                    new byte[plainTextBytes.Length + saltBytes.Length];

            // Copy plain text bytes into resulting array.
            for (int i = 0; i < plainTextBytes.Length; i++)
                plainTextWithSaltBytes[i] = plainTextBytes[i];

            // Append salt bytes to the resulting array.
            for (int i = 0; i < saltBytes.Length; i++)
                plainTextWithSaltBytes[plainTextBytes.Length + i] = saltBytes[i];

            // Because we support multiple hashing algorithms, we must define
            // hash object as a common (abstract) base class. We will specify the
            // actual hashing algorithm class later during object creation.
            HashAlgorithm hash;

            // Make sure hashing algorithm name is specified.
            if (hashAlgorithm == null)
                hashAlgorithm = "";

            // Initialize appropriate hashing algorithm class.
            switch (hashAlgorithm.ToUpper())
            {
                case "SHA1":
                    hash = new SHA1Managed();
                    break;

                case "SHA256":
                    hash = new SHA256Managed();
                    break;

                case "SHA384":
                    hash = new SHA384Managed();
                    break;

                case "SHA512":
                    hash = new SHA512Managed();
                    break;

                default:
                    hash = new MD5CryptoServiceProvider();
                    break;
            }

            // Compute hash value of our plain text with appended salt.
            byte[] hashBytes = hash.ComputeHash(plainTextWithSaltBytes);

            // Create array which will hold hash and original salt bytes.
            byte[] hashWithSaltBytes = new byte[hashBytes.Length +
                                                saltBytes.Length];

            // Copy hash bytes into resulting array.
            for (int i = 0; i < hashBytes.Length; i++)
                hashWithSaltBytes[i] = hashBytes[i];

            // Append salt bytes to the result.
            for (int i = 0; i < saltBytes.Length; i++)
                hashWithSaltBytes[hashBytes.Length + i] = saltBytes[i];

            // Convert result into a base64-encoded string.
            string hashValue = Convert.ToBase64String(hashWithSaltBytes);

            // Return the result.
            return hashValue;
        }

    }
}

Have called this helper function my controller before saving the password to table and saved

Code consits of salt,hash and base 64

Because we support multiple hashing algorithms, we must define hash object as a common (abstract) base class. We will specify the actual hashing algorithm class later during object creation.