Wall was removed, lentil beam installed and building surveyor signed off the work
Which means the wall was structural which then makes it, by law, Owners Corporation common property. You really had no right to touch it without the OC’s permission.
Am I obliged to comply with allowing a third party to review the work?
Considering you had no right to alter property that is not actually yours, you had better seek the OC’s retrospective approval. I’d be agreeing if I was you. The OC could otherwise make you restore it.