Truleconcerned
what you have described is that the OC limited the powers of the strata manager.
Thats a pretty easy thing to do.
Sacking a strata manager is very difficult. Firstly their contract will dictate the conditions that they can be sacked for (and incompetence is not one of the conditions). Secondly they can be removed by a court if found guilty of some criminal offence (eg fraud) but the OC has the burden to prove their case, which is time consuming and expensive.