@Rafael-Estevam, what you say to Alexa will make more sense if you make the Voice field just computer instead of turn off computer.
The formula is, "Alexa, turn on/off [voice word]."
That's assuming you're using the TRIGGERcmd Smart Home skill.
In this example, I can say
"Alexa, turn on calculator." to open it.
"Alexa, turn off calculator." to close it.
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