How to Say "shut down" in Spanish
The Spanish word for “shut down” is “apagar” — A1 level. This is a very common word in everyday Spanish.

Examples
Por favor, apaga la luz antes de salir.
Please turn off the light before leaving.
Tienes que apagar el móvil en el cine.
You have to turn off your cell phone in the movie theater.
Apagué la computadora y me fui a casa.
I turned off the computer and went home.
The G-to-GU Change
To keep the hard 'g' sound (like in 'go'), 'apagar' changes its 'g' to 'gu' whenever the ending starts with 'e'. This happens only in the 'yo' preterite form (apagué) and throughout the present subjunctive (apague, apagues, etc.).
Using 'apagar' for people
Mistake: “Apagué a mi hermano (I turned off my brother).”
Correction: Use 'callar' (to silence) or 'hacer silencio' (to make quiet) when referring to stopping noise from a person. 'Apagar' is only for objects or flames.
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