SQL Server, delete if exists, insert if doesn't exist (aka toggle)

toggle.sql

MERGE INTO SIJL.USERS AS target
USING (
    SELECT '<username>' AS username, '<email>' AS email
) AS source
ON (target.username = source.username AND target.email = source.email)

WHEN MATCHED THEN
    DELETE

WHEN NOT MATCHED THEN
    INSERT (hash, first_name, last_name, email, username, age)
    VALUES (HASHBYTES('SHA2_256', '<password>'), '<first_name>', '<last_name>', '<email>', '<username>', <age>)
;