To upgrade from HST 1.0.x to SmartSense 1.2.0, please first remove HST 1.0.x from all hosts:

# rpm -e hst
# rm -rf /usr/hdp/share/hst
# rm -rf /etc/hst
# rm -rf /var/log/hst

Once this is complete, see the Installing SmartSense without Ambari section.