How to remove PIN to make it work under Android?

[BarsMonster]

I see that keys with PIN are not yet supported in Android. I tested it - and indeed, no luck with both Firefox mobile and Chrome mobile.

Aldo Bleeker suggest that to make it work under Android to "Remove the PIN first when you try to register it on Google, or you won’t be able to enter a name. I just added the PIN afterwards again.".

But how to remove PIN? Change pin using solo1 app (with fido2==0.9.3) does not work as PIN must be at least 4 digits long...