Supposedly a word is in usage quite a few years before it hits the dictionary. So when I find a word with an origin near my time frame, I'm fairly safe using it.
It's also possible to make an executive decision to use an incorrect word knowing it isn't correct for the time frame—if the writer thinks it will have more impact on the story.
One quick and easy reference source, http://etymonline.com/ is an amazing help to research words of the past.
I checked delete. It's listed as being in usage from the 1600's. So it's possible computers have been deleting things for hundreds of years.