Education Secretary Terrel H. Bell hjas sharply reduced the number of top-level jobs in his department, explaining that it had "too many chiefs for our small size."

Bell said he has eliminated four of 13 assistant secretary positions and 35 of 47 deputy assistant secretaries. Each of the posts paid more than $50,000 a year, he said, and had several special assistants attached to it, who also will be cut.

"I would have eliminated more of the assistant secretaries if I could have," Bell said, "but they're required by statute. There's just an enormous administrative superstructure in the department, and well be better off without it."

President Reagan said during the 1980 presidential campaign that he would eliminate the Department of Education, which was approved by Congress in late 1979, with strong support from former president Carter, and began operations 10 months ago.

With 13 assistant secretaries, the department had more officials at that high rank than any other Cabinet department except Defense and State. Bell said the number of deputy assistant secretaries also was among the highest in the government, even though the Department of education is relatively small with about 17,000 employes and a budget of $14.5 billion.

Among those being eliminated is the assistant secretary for non-public education. Bell said private-school groups had asked him to keep the position, but he plans to replace it with a lower-status speciai assistant.

The functions of two other posts being eliminated -- the assistant secretaries for management and planning -- are being transferred to the department's undersecretary, Bell said. Two other posts -- legislation and public affairs -- will be merged.