"I DON'T FEEL a bit sorry for anything that I've done," Ambassador Andrew Young observed in resigning yesterday. Well, he may not feel sorry, but he should. Mr. Young inflicted genuine damage on his friend, President Carter. His earlier transgressions were mere irritations compared with this one, for it undercut the president's valuable and infinitely fragile strategy to build peace in the Middle East.

At first Mr. Young said that it was only by chance that he ran into the Palestine Liberation Organization's spokesman last month, and of course there was no mention of business. Later, under further and sharper questioning, Mr. Young acknowledged that the meeting was not entirely by chance after all and, as a matter of fact, they happened to discuss a forthcoming vote in the Security Council. The United States has repeatedly given Israel the most categorical assurances that it will neither recognize the PLO nor negotiate with it until it recognizes Israel's right to exist. Mr. Young didn't bother to let the State Department know, he said, about the conversation. As for his first version of the affair, he passed it off with the disingenuous comment, "That was not a lie, it was just not the whole truth."

In the past, it has sometimes seemed a tradition that the White House and the State Department periodically embarrassed and humiliated the American ambassador to the United Nations. There was, memorably, the Kennedy administration's order to Adlai Stevenson to denounce and deny the Cuban accusation of American complicity in the Bay of Pigs invasion. But this time, conversely, it was the ambassador to the U.N. who embarrassed and humiliated the State Department and the White House. A historian might think of it as Adlai Stevenson's revenge.

The importance of the incident arises from the Israelis' growing fears that the United States might be inching toward precisely this kind of dealing with the PLO. It was a further fragment of evidence to hint at the Israelis' nightmare of betrayal. The United States could hardly have made a more explicit and binding commitment not to do what Mr. Young did -- and he then passed it off as no more than a commonsense solution to an unreasonable prohibition.

As a diplomat, Mr. Young persistently refused to accept the discipline of his temporary profession. Mr. Young never accepted the idea that, as long as he was an ambassador, he was inescapably speaking for his government. This was too bad: As U.N. ambassador, he made some truly valuable, outsized contributions to American diplomacy. He helped to establish vital links between this country and other (mainly Third World) countries that had never before been either hospitable to or comfortable with American policy. But it is important to remember, in this connection, that it was Mr. Young himself who put these gains at risk by persistently refusing to accept the inconvenience of verbal discipline and restraint. On the contrary, he liked to think that, from time to time, he could choose to speak only for himself. But it didn't work. Now he has finally resolved the confusion.

In resigning, he has done the right and necessary thing. Mr. Young is one of the most interesting and attractive figures in American public life, but he was miscast at the United Nations. By resigning he has done a service to President Carter and, quite possibly, to himself.