(1)    The department or permit officer may refuse to grant a street trade permit and identification card to a minor who seems physically unable to perform the work or whose school record indicates that the minor should not undertake such employment in addition to school, or whenever in the judgment of the department or permit officer the best interests of the minor would be served by such refusal.

   (2)   The department may revoke a street trade permit and identification card if the minor for whom such permit was issued is found by the department to have worked when prohibited under s. 103.24, if it appears to the department that such permit was improperly or illegally issued or if in their judgment the best interests of the minor would be served by such revocation. The department shall by registered mail notify such minor and the minor’s employer of such revocation. On receipt of such notice the employer shall immediately return the revoked permit and discontinue the employment of such minor, and the minor shall immediately return the revoked identification card to the permit officer.