How to resolve - ERROR: cannot cast type numeric to boolean

There is no direct cast defined between numeric and boolean. You can use integer as middle-ground. 

ALTER TABLE <schema>.<table_name> ALTER <column_name> TYPE bool USING (<column_name>::int::bool);

Ex:

ALTER TABLE SANGA.SANGA_H_TRANSACTION_DETAILS  ALTER is_active TYPE bool USING (is_active::int::bool);