You may choose to untap Macie during your untap step. If you do, the chosen effect will immediately end if its scheduled duration has already elapsed. This also happens if Macie becomes untapped some other way at some other time or if Macie leaves the battlefield.

If Macie becomes untapped or leaves the battlefield and the chosen effect’s scheduled duration hasn’t already elapsed, the effect will continue until that time. You can use Macie’s last ability again to make sure it doesn’t end during the cleanup step.

Removing pause counters from Macie won’t cause her to untap and won’t cause the chosen effect to end.

If Macie becomes untapped before her last ability resolves, you won’t choose any effect to not end.

The chosen effect can be from any source, including one controlled by an opponent.