if company cannot change the consitution can the comany take shares from robert?

Robert acquired 2000 shares in his own name and 6000 shares in the names of nominees. This gives Robert 24.65% of the voting power of the company. The shares have been registered in the names of nominees because the Board did not know of the nominees. Robert is a former director and also holds preference shares issued to him when he initially joined the company board of directors. There are six current directors. The three who have been directors since the company was first set up also hold preference shares.

How can the shares be registered in the names of the nominees if they did not know their names?

Voting goes to the names on the shares. Period. Robert does not own them.