How much use did the word 'delete' get before the technological boom?
Etymology online offers the following:
delete
late 15c., "destroy, eradicate," from L. deletus, pp. of delere "destroy, blot out, efface," from delevi, originally perf. tense of delinere "to daub, erase by smudging" (as of the wax on a writing table), from de- "from, away" (see de-) + linere "to smear, wipe" (see lime (1)). In English, specifically of written matter, from c.1600. Related: Deleted; deleting.
(and related)
dele
typographer's direction to blot out a letter, from L. dele, imperative singular of delere (see delete).