On the walls next to the grainy, enlarged photographs of old women and hungry black children are signs that say things like, "10,200,000 poor Americans are children," and "6,400,000 Americans work but are still poor."

Scrawled on the flip chart at the front of the room, a new message said: "The jobs are at Defense."

The scene was a job seminar for employes of the Community Services Administration, which officially shuts its doors today. It is the first significant federal agency to be wiped out since World War II and, if the Reagan administration has its way, it won't be the last.

For the agency's employes, the end was a hectic blur of 10-hour days (a bureaucratic requirement to fill out their final pay period), union protests, job hunting, anxiety over whether Congress would approve money for severance and lump-sum leave pay, and sadness over the end of an effort to which many of them had felt a personal commitment.

After today, there will be at least 30 percent less money for community programs for the poor and, as veteran anti-poverty worker David Cohen put it, "the symbol of federal commitment will be gone. No longer is there any one place in the federal government whose single purpose is to fight poverty."

Most control over a maximum of $363 million in block grants (possibly less) for 1982 now goes to the states. And in place of more than 900 CSA employes nationwide, officials said, a few dozen employes already at the Department of Health and Human Services will administer the money.

The cost of closing CSA is expected to be about $30 million, including $12 million for severance and leave pay to employes, according to director Dwight Ink. The administration expects the move to save tens of millions a year in the long run; the agency's administrative costs this past fiscal year were $42 million.

In emotional graffiti scrawled all along the corridors of their building, employes vented their bitterness and frustration against the administration over what they see as the unnecessary harshness of the closing. Some walls are simply a final roster, filled with the crayoned autographs of the departing workers.

More than 60 employes of CSA, which used to be called the Office of Economic Opportunity, have worked there since it began in the heady burst of 1960s idealism. They watched the agency evolve from a band of brash, anti-establishment crusaders, proposing to eradicate poverty in 10 years, into an institutional animal plagued with more conventional problems of low budgets and poor management.

In the early days, they were confrontational, often heedless of local officials, or mobilizing busloads of poor people to lobby in Washington, veterans recalled this week.

At first, said Cohen, a grants administrator who has worked at the agency for 16 years, "There was certainly a call to arms. You know, the mayors were 'evil' and the poor people were good and pure of motive. I'm exaggerating, but there was this sort of attitude . . . ."

The poverty fighters wanted to channel power to the disenfranchised poor and there was admittedly, he said, "a certain naivete" in the belief that they could make it work "even though it might require stepping over the local leadership."

Beginning in the late 1960s, local officials were given a bigger role in the effort and the agency switched from confrontation to cooperation with local governments. With Reagan's plan to cut the federal role and shift power to the states, that trend now comes virtually full circle.

Now some employes find themselves preoccupied with their own impending unemployment as well as the deprivations of the people they've tried to serve.

In the last couple of weeks, between 300 and 400 CSA employes signed up for counseling on welfare, food stamps or unemployment insurance, according to outplacement director Robert Wilcox.

Out of 470 employes who signed up for job placement services, 153 have found other jobs, with the Defense Department the most active recruiter, Wilcox said. Around 55 more report jobs in the offing. Some 200 of the total workforce were eligible to retire.

Some CSA employes will continue in temporary positions helping place their co-workers in new jobs (using facilities provided by the. Office of Personnel Management) and other close-out activities.

A lawsuit brought by their union, the American Federation of Government Employes, could enable a few of the CSA workers to transfer temporarily to HHS.

"The clerks, computer specialists and others with transferrable skills will have the easiest time finding new positions," said Barbara Morgenstern, a private placement specialist whose firm was hired by CSA. The hardest to place, she said, will be those trained specifically in the social sciences.

"I've sent out lots of forms, but I haven't heard anything positive," said CSA social science analyst Eddie Capers, 28, whose job was to evaluate anti-poverty programs. "It seemed a very good field at the time I got into it."