throwaway account; burner account
Internet slang for a disposable online account used temporarily, often to avoid linking to one's main identity.
I posted the controversial opinion using a throwaway account.
I created a burner account and asked the question anonymously.
Standard internet slang spelling using ateji for 垢 (アカ).
Mixed kanji-katakana spelling, also common.
From 捨てる (to throw away) + 垢 (slang abbreviation of アカウント, from English 'account'). The kanji 垢 is ateji used for its reading アカ.