RELUCTANTLY, defiantly and with scant remorse for the legacy of his final years in office, Marion Barry has at long last said he won't run for reelection. That has to be a source of great relief in this city, though as he himself stated, the step should not be related to his legal situation. It should have nothing to do with any plea-bargaining, nor does it remove the immediate clouds over the local government that Mr. Barry still runs; he has not resigned and the term for which he was elected has nearly half a year to go. But now, at least, the candidates who have been in the contest for mayor -- who, with only a couple of exceptions, have been far too deferential to the man they seek to replace -- should move out and speak out far more forcefully than they have for better government.

Mr. Barry may continue as he did last night to portray his decision to leave office as an act of magnanimity to save the troubled people of his city, but painful as it may be to dwell on it at this time, it was he who delivered the ultimate troubles. If the charges against Mr. Barry are proven, they will amount to a terrible betrayal of public trust. The very constituents Mr. Barry claims to have served best are those who have been victimized most -- those who looked to him for strength and example in their struggle with drugs and the murdering of their young.

While this transition can now accelerate, the personal tragedy of Marion Barry -- medical and legal -- is real and remains. His own recovery and that of the city will both be impeded so long as he stays in office. Nevertheless, this process of recovery now stands at least a somewhat better chance insofar as both the mayor and the city are concerned with his removal of himself from the coming election. It cannot have been easy for Mr. Barry to renounce further claims on his office, but he was right to do so.