It doesn't have a de-select parcel option in the selected(drawn) parcels.
Check out the Public Notification widget in Web AppBuilder that's coming in the December update of ArcGIS Online. Improvements have been made to interacting with parcels. Give this a try next week and let us know if this meets your needs or still have functionality suggestions.
In January 2018, the Public Notification application has been replaced by a new Web AppBuilder configuration.
Public Notification | ArcGIS for Local Government
The version referenced in this post has been moved into mature support.
Retrieving data ...