Close your router to all unauthorized hosts first:

conf term
  ip access-list standard acl_snmp
    permit 192.168.1.1
    deny any
  exit


Then enable explicitly shutdown via snmp set:

snmp-server system-shutdown
! Enables system shutdown using the SNMP message reload feature.
snmp-server community verysecret rw acl_snmp


From your management host issue:
$> snmpset -v1 -c verysecret targethost.domain .1.3.6.1.4.1.9.2.9.9.0 i 2

Your router / AP will be immediately reloaded.