The departure of the pair was confirmed following an internal review of their conduct and behaviour as shown in the recent Belfast rape trial.
The IRFU and Ulster Rugby have been carrying out a review into the players' future in the wake of their acquittal on rape charges last month.
Two weeks ago, the two men were found not guilty of rape following a nine-week trial at Belfast Crown Court.
Protesters outside Ravenhill this evening.
The latest protest against the duo saw dozens of people stage a protest on Friday outside the stadium in Belfast ahead of Ulster's Pro14 match against Ospreys, the side's first home game since the trial.
The IRFU also announced that they intend to ensure that these core values are applied across the board.
A female Ulster supporter, who asked not to be named, said: "I Think it's a load of nonsense, the guys have been tried for what they were accused of and that's it".
"I said outside court that the Stuart Olding that you read about in the trial is not the real Stuart Olding".More news: Search for vanished family turns up woman's body
'The treatment that I have received since my acquittal, both fair and unfair, has made me even more determined to prove myself. I bear no one any ill will.
Former Ulster and Ireland captain Willie John McBride added his considerable weight to the debate, saying both players should be allowed to resume their careers.
Both players have expressed disappointment and regret at the move.
"I am very sorry that this day has come to pass".
'To those who have supported me through these last 20 months and especially the fans who continue to support me, I thank you all'.
"It is therefore with great sadness and regret but with many cherished memories that I leave that behind".
Two other men, friends of the Ulster stars, were also acquitted on separate charges, including exposure and perverting the course of justice.
Kellie Turtle, an organiser of the "Stamp out Misogyny at Ulster Rugby" protest said: "This is to send a message to Ulster Rugby and the IRFU to take action on what we see as a very worrying underbelly of sexism and misogyny".