Robert J. Myers, a Republican and one of the most respected Social Security experts in the nation, has resigned as deputy commissioner of the program with some harsh words for the Office of Management and Budget for "disastrous" meddling and political and policy misjudgments on Social Security.

He was referring specifically to OMB decisions to ask Congress to repeal the Social Security minimum benefit for 3 million people already on the rolls and to increase the penalty sharply for choosing to retire at 62 instead of 65.

Myers had privately opposed these proposals as as bad policy and bad politics, and had warned that they would undermine the administration's Social Security revision program.

The proposals ignited a storm of public protest and gave the Democrats an opportunity to batter President Reagan on Social Security.

In what is generally considered the worst political defeat of his term in office, Reagan eventually was forced to ask Congress to restore the minimum benefit for those on the rolls after it had repealed the minimum benefit at his request, and to withdraw his entire Social Security legislative plan. The bill restoring the minimum benefit cleared Congress last week.

Myers was chief actuary of the Social Security system from 1947 to 1970, then a long-time outside adviser to Republicans on the House Ways and Means and Senate Finance committees, which have legislative authority over the program. He became deputy commissioner for programs in March, and has been a major source of credibility for the administration on Capitol Hill.

In a letter of resignation this week to Health and Human Services Secretary Richard S. Schweiker, Myers said he supports the general principles and most of Reagan's legislative requests on Social Security and hopes to contribute to their enactment from outside the government.

He said he is leaving because it appeared there would be no long-range Social Security bill, which is what he wants to work on, for several years.

But he added that, in developing legislation, there were too many "layers of clearance and review--not only as to major political issues, but also as to minor policy and technical points--at levels above the Social Security Administration. This occurs both in the department and in higher organizations, such as the OMB.

"In particular the latter agency (and especially its civil service employees) develops policy without regard to the social and economic aspects of the Social Security program--and even the political aspects. This was well exemplified by the disastrous results that occurred from the proposal to eliminate the minimum benefit for all persons currently on the rolls and also from the proposal to sharply increase the early-retirement reduction factor."

Sen. Daniel Patrick Moynihan (D-N.Y.), a sharp critic of the president's Social Security cut proposals and a member of a newly appointed presidential commission on financing of the system, called Myers a man of "integrity and experience."

He said he was not surprised that Myers has "found it necessary to resign" because "it has been painfully clear that policy-making in the Social Security administration has been thoroughly politicized."

House Social Security Subcommittee Chairman J.J. (Jake) Pickle (D-Texas) said Myers' resignation is "bound to hurt" the Social Security administration and "should cause the administration to re-examine its reliance on deep cuts."