I have a past that I want to erase.
I erased all the data by mistake.
After you leave the classroom, please don’t forget to turn off the light.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means extinguish so the verb vocab version is to extinguish. You can also use this word to refer to turning something off (like lights). Technically you're extinguishing the lights or power, right?
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: The kettle is getting too hot so it catches on fire. You have to extinguish the flames before your house burns down too, just because of this stupid little kettle.