How can I decrypt hash password with salt?

To decrypt hash password with salt, you must understand that hash functions are designed to go only one way. If you have a password, you can easily turn it into a hash, but if you have the hash, the only way to get the original password back is by brute force, trying all possible passwords to find one that would generate the hash that you have. Assuming the salt is very long, not knowing the salt would make it nearly impossible to crack (due to the additional length that the salt adds to the password), but you still have to brute force even if you do know the salt. As an example, let's say that the password is "secret" and the salt is "535743". If the salt is simply appended to the end of the password, then the hash you'd be cracking would be a hash of the string "secret535743". Without knowing the hash, you'd have to try all possibilities until you reach "secret535743", which would take quite a while due to its length (keeping in mind that real salts are much longer than this).

But if you know that the salt is 535743 and that it is appended to the end of the password, then instead of trying everything, you'd try "a535743", "b535743", "c535743", etc. This greatly reduces the number of possibilities you have to try until you reach the correct string. With that being said, it is generally quite rare to have a situation where you know the hash but not the salt since both are usually stored in the same place.