The names of two candidates for an at-large City Council seat would be removed from the July 19 special election ballot if the D.C. Board of Elections and Ethics adopts recommendations framed yesterday by board counsel Winfred R. Mundle.

Following a hearing yesterday, Mundle announced that he would ask the board Thursday to strike down the candidacies of Frank E. Sewell Jr. and Naomi T. VanderJagt because their candidacy petitions lacked the minimum number of valid signatures.

Sewell and VanderJagt each had tried to run as a candidate of the Statehood Party and had to submit 19 valid signatures of party members to run in the election to fill the vacancy created by the death March 23 of Julius Hobson Sr.

Mundle determined yesterday that at least 10 of the 28 signatures turned in by VanderJagt were not those of persons properly registered as Statehood Party voters. In the case of Sewell, Mundle said, four of the 20 signatures submitted were those of registered Democrats.

The candidacies of both were challenged by the Statehood Party, which also has asked that a third candidate, Leo A. Murray, be removed from the ballot. In a previously undisclosed challenge, the party contends that Murray should not be allowed to run under the party's label because a officially endorsed at a party convenfourth candidate, Hilda M. Mason, was tion.

That challenge is to be heard later this week, along with another one to the candidacy of independent Susan Truitt. Decisions of the board can be appealed to the D.C. Court of Appeals. Neither VandeJagt nor Sewell appeared at yesterdays hearing.