I would say that it was not literally removed during their lifetimes, for that could
not have happened until the institution of Baptism.
When was Baptism instituted? I have heard it taught that happened when Our Lord
said, "Going therefore teach ye all nations: baptizing them in the name of the
Father, and of the Son, and of the Holy Ghost" (Matt. xxviii. 19). This was at the
moment before His Ascension into heaven.
But that does not apply to those who had already died. For them, there could
have been a sort of anticipation of the sacrament, by which they were secure in
the "bosom of Abraham" until such time as Our Lord came to release them. This
could have happened at the time of His death, when the Creed infallibly teaches
us that He "descended into hell." That is, when He went to the "bosom of
Abraham" to set free those who waited there so they could then enter eternal
beatitude. It would seem then, that the actual removal of their stain of original sin
occurred at that "time," when Our Lord descended into hell. If that is the case,
then it would seem that would be a subject for artistic embellishment, but I am
not aware of any depictions of that in art or verse.
His descent into hell could have also been more than that, but the pertinent part
is this: the release from original sin and its consequences, of those from the Old
Testament, who were not damned.
At what point was original sin removed from Old Testament saints?
Certainly they had original sin, for all of Adam's children have it. And certainly it
needs to be removed for them to enter heaven. It would not need to be removed,
however, for them to go to hell.
Was [it] removed when they got circuмcized?
Circuмcision would not have removed it, but it could have given the recipient a
kind of grace that contributes to his salvation inasmuch as he was complying
with the law of God, and doing His will.
Was it removed just before they died?
It would not have been removed before they died, for there was no sacrament
in the old dispensation. Nor was there anything else they all did before they died
that could have removed it. Nor is there any teaching that provides for such
removal of original sin before they died, for whatever reason.
Was it washed from them after Jesus' death while they all were held in Abraham's bosom? or was it removed at some other time and some other way? What say you all?
See above.