Hugh W. Cadden, President Carter's choice to fill a vacancy on the Commodity Futures Trading Commission, yesterday gave up his job as aide to CFTC Chairman James Stone.

Cadden will take a vacation, then wait and see what happens with his controversial nomination, a CFTC spokesman said yesterday.

By leaving this week, Cadden kept his options open in case he does not get the CFTC commissioner's job. New federal rules which go into effect Monday severely restrict government employes from leaving to work in the same field in private industry.

Cadden was the CFTC's director of trading and markets until last spring, when he resigned, saying he planned to return to private law practice. But at Stone's request, Cadden stayed on temporarily as special assistant to the chairman.

Earlier this month, the White House said President Carter would nominate Cadden for a vacant CFTC commissioner's job. But the Senate Agriculture Committee which must approve the appointment warned that the nomination would be rejected and urged Carter not to make it.

Officially the White House says Cadden is still its choice, but there has been much speculation that his nomination never will be sent to the Hill.