Apocalypse means in fact "put away the cover", that is "removing the cover", and then things will be revealed (cf "book of Revelations").
Apocryphal means "hidden away", because they are not to be read. In fact, apocryphal Gospels would be extremely dangerous for Christian believers : the one from St-James mentions explicitly that Jesus had brothers and sisters (and not in a symbolic meaning) and married St-Magdalena ; the one by St-Peter, yes, himself, does not mention the Resurrection, etc..
The word does not mean by itself "spurious", but if it was impossible to deny their existence - they were too well known, at least you could deny their authenticity and forbid their reading.
Apogee means "away from earth" and applied initially to the moon.
Apotheosis means "put away to rejoin the gods".
You see that "apo" is always used in the consistent meaning of "away, off"