Hi Shan,
For the latest version of TPC this can be accomplished by running the following JavaScript code on your widget:
$(findControl(".CrmBoolean_C005").get_booleanControl()).find("input").prop("checked",false);
Submitting the form with a null value is undefined behaviour, the null value may be submitted to CRM as NULL or it could default to "No"
Regards,
Clinton
Last modified on 12 Nov 2015 19:11 by Clinton Bale