JDBC support for DROP USER?

Good People,

We are getting an exception when trying to drop a user with a JDBC
PreparedStatement.  Is this supported?  Here is the response we are seeing:
  java TestPrepare  error : ERROR: parser: parse error at or near "'" 

Thanks in advance for any insight.  The sample source code follows.

Best Regards,
//Dave


import java.sql.*;

public class TestPrepare {
  public static void main(String[] args) {     try {        Class.forName("org.postgresql.Driver");     } catch (Exception e) {        System.out.println("load driver fails");        return;     }     try {        Connection con =
DriverManager.getConnection("jdbc:postgresql:///",                                                     "",
"");        String dropUserSQL = "drop user ?";        PreparedStatement dropUserPs = con.prepareStatement(dropUserSQL);
        String userName = "tester";        dropUserPs.setString(1, userName);
        dropUserPs.executeUpdate();     } catch (SQLException e) {        System.out.println("error : " + e.getMessage());        return;     }  }
}