Afaik, if owners get together, regardless of the number and call ( formally ) to a meeting, notifying, etc and then vote, unless there are ( formal ) objections, whatever they decide it stands. However, it is always best to have as many people as you can on the same page and with the same interest, because any decision that is not backed by many, will lack legitimacy. 2/3 are not necessary in any case https://ligadelconsorcista.org/sobre_revocacion_del_mandato_administrador we have a building with 80 owners and 70 garage spots owned individually ( not all of them owned by apt owners ). We removed the managers with the votes of around 50 owners in total, no objections. The actual problem I see here is tht it is just Jantango trying to do this, and interested in the matter.Then again, to have the aforementioned meeting, you need first 66.66% of the owners signatures.
Jantango already mentioned the absence of a Council so the 2/3 in agreement is a must. THEN and only THEN you can proceed with yous simple majority of those present AND subject by the vote of those absent that have x days to send a vote (following more procedures). Just the simple majority won't put an end to it. There are Musts, before and after.