Zelenskyy does not have the power to call off joining NATO. The Ukraine parliament changed the constitution to state explicitly that joining NATO is a Ukrainian goal.

Just like in the US, the president saying something doesn't make it happen. Obama promised he'd close Guantanamo in 2008, which would have been great. It is still open in 2023.

In addition, Zelenskyy went back and forth on NATO membership in the weeks and months prior to the war.