CREATE TABLE table_16568 ("Character" CLOB, "Portrayed by" CLOB, "Relationship" CLOB, "First appearance" CLOB, "Last appearance" CLOB)

What episode was the last appearance of the character, rikki sandoval?
SELECT "Last appearance" FROM table_16568 WHERE "Character" = 'Rikki Sandoval'
SELECT "Last appearance" FROM "table_16568" WHERE "Character" = 'Rikki Sandoval'