One way to hold this word: a page with writing on it, and a hand passing over the writing until you cannot read a single letter. The paper is still there. The marks may even still be there. What has gone is the thing you could read. Every other use of obliterate does that same move to something bigger — a building, a view, a memory — and the test is always the same: go and look, and there is nothing left to make out.
From the word’s history
Wiktionary derives obliterate from Latin obliterātus / oblitterātus, the participle of obliterō, probably from ob- ('against, towards') plus littera ('letter') — literally to blot out written letters. The writing sense is therefore the one closest to the word's own parts.
字典說 obliterate 借自拉丁文 obliterātus／oblitterātus，是 obliterō 的分詞；這個動詞很可能由 ob-（對著、朝向）加 littera（字母）組成，字面上就是「把寫下的字塗掉」。所以「抹掉字跡」這個用法，最貼近這個字本身的組成。
Wiktionary via kaikki extract, source_ref kaikki:3f6f69a190036ae4:512180880 (etymology 1 of obliterate)
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