Settings 2 tab [x] Do not send pet to attack
Likewise for mercs, [x] Disable Merc Support
These do the same thing for their respective names. It won't do anything with your (pet/merc). That includes sending it to attack, changing it's target etc. You can manage that, OR have Ogre manage it for you.
(Doing a /pet backoff apparently modifies those, and Ogre uses that)