Have a user question if the +- can be removed from the Numbers appearance. They love that the . goes away for int but then asked why the - cannot be removed.
By setting the appearance value to numbers, a highlighted integer question will be accompanied by a custom numeric keyboard to enter a value. The keyboard also includes a button to make the value positive or negative.
This is not currently possible but I'd encourage you to log an enhancement request through Esri Support so we can assess this one.
In the meantime, would a constraint work? Could use .>=0 to ensure the number entered is positive. Appreciate it's not quite the same as controlling the input at the time of input!