Salam i want to know that if masturbation is indeed a major sin but is it adultry or is it fornication and can someone repent or ask forgiveness from it? Are there anyways for it to be erased?
Brother, i would assume that you use google translate to translate the word "zina" into English. So there might be some misunderstanding. If you look up the definition of Adultery, there is no way masturbation is classified as adultery. And Fornification, is an act that require a partner, so Masturbation is not fornification.
Staying to the question, how do you repent? By not doing it. And ask forgiveness to Allah. if you want, you can do Salat Al Tawbah.
And indeed you can repent and ask forgiveness to Allah SWT for every sin.
"Say, "O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah . Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful." (Translation by Sahih Int.)
Az-Zumar verse 53
And Allah knows best.