Wait, if she can alter time however she desires, then... why not just alter time so she remembers to put in the shutdown override, before giving it to Chronoa?

That would result in a causality loop. Alter time to remember the override -> Chronoa is back to normal -> No need to alter time to remember the override, so no altering of time -> Alorna forgets the override -> Chronoa is once again brainwashed.

That's assuming that the new timeline doesn't overwrite the pre-existing timeline or cause the timelines to merge, a la Back to the Future, or Red Alert 2, thus nullifying the Causality Paradox.

Dragon Ball is weird when it comes to that. It runs on multiverse theory except when it doesn't. So the most causing a causality loop would do in this case normally is result in two parallel timelines and slightly destabilize the fabric of space-time. Problem is, whatever method both the Timebreakers and the Time Patrol use doesn't respect this, and instead alters the same timeline. And the result is a timeline overwrite _plus_ significant levels of time-space instability as a result.

So, I guess your idea could work, but it could potentially cause all of reality to basically BSOD in the process.

Honestly, figuring out a manual way to disable the tiara would be a safer bet regardless.

Just tell her to take the thing off and act as if she'd never put it on? I mean, it's a soft override, right?