Sessions can un-recuse himself as he recused himself under the wrong statute and there is no Russia-Trump campaign collusion or evidence of the same. Trump can fire RR as he is the head of the Executive branch and all beneath him serve at his pleasure.
The majority of the American public would support the move to fire Meuller and Rosenstein as they are costing taxpayer money and distracting from the job of governing when there is no evidence of collusion by the Trump campaign with Russia. Hillary lost because she is dishonest and corrupt and Americans knew it. The USA is being diminished because POTUS is placed under a dark cloud of suspicion when he is entirely innocent.
Any decent prosecutor with professional ethics seeks to quickly exonerate an accused person when the evidence points to innocence. Justice delayed is justice denied.