Arduino Industrial 101 factory reset

Hi, I found the topic: where someone noticed that it's unclear how to do an Arduino Industrial 101 WIFI reset to defaults. However, I would be more interested in how to reset the board to factory defaults (As this can be needed in industrial IoT whenever a new setup is needed).

How is it possible to do a factory reset of the Industrial 101 and get the Wifi setup page back?

The question is now on Stackoverflow, too:

Hi, for me worked pressing user1-reset-button for >30sec and then switch off and on again! But it makes a full reset, sketch is also gone then.

I cannot test it because I do not have the Arduinos any longer. Maybe it works for others but when I tested it, it didn't work that way.