Clearing value of a DatetimePicker

[thuydotm]

Description of expected behavior and the observed behavior

Not sure if this is a bug or a new feature to Panel. Let's say I have a layout consisting of a button named "Edit", a DatetimePicker disabled with no default value, and a button named "Submit". At the time of initialization, the value of DatetimePicker is Null. The way these objects interact is as follows:

• Click "Edit" button, DatetimePicker is enabled so user can select a specific time value.
• Click "Submit" button, the selected time value will be pushed to the DB, and the DatetimePicker will be disabled and reset back to Null.

I have tried several ways with no success in clearing the value of the DatetimePicker.

Complete, minimal, self-contained example code that reproduces the issue

time_widget = pn.widgets.DatetimePicker(disabled=True)
time_widget.value = now()

# how to set value back to None?
time_widget.value = None/pandas.NaT/np.nan => all causes error