How can I close DataFieldAlert from code

I'll try my luck again, maybe someone has a good idea

I'm gonna be Captain Obvious and venture a guess that there's no way to do what you want. It appears to be a limitation by design that a datafield alert can't close itself. Just my opinion but we see this kind of limitation all the time (I'm not passing judgment) and Garmin never seems to reverse itself on this kind of apparent design decision.

As far as setting the timeout on a real device, I don't think it's possible, but I'm only judging by the device that I own - 945LTE - and the following text in the docs:

[https://developer.garmin.com/connect-iq/core-topics/native-controls/#alerts]

Alerts

Since API level 3.2.0

When you want your data field to notify the user of a specific event, you can push a view that extends DataFieldAlert. DataFieldAlert is a special instance of View that can be presented to the user with showAlert. The alert does not accept input and will time out after the standard alert period. The user is required to enable alerts for your app in the workout alert settings.

CYBERMAN54 said:

But it never disappears.

CYBERMAN54 said:

How can i make the alert disappearing after the "standard alert period"?

I assume you mean in the simulator.

I think in the simulator, you have to use Data Fields > Timeout Alert as described in the OP, but on a real device it will time out by itself.