DELETE u2
FROM
usersRelation u1,
usersRelation u2
WHERE
u1.selfId = u2.selfId
AND u1.bossId = 263
AND u2.bossId = 1
DELETE u2
FROM
usersRelation u1,
usersRelation u2
WHERE
u1.selfId = u2.selfId
AND u1.bossId = 263
AND u2.bossId = 1