Removing an app protected from uninstall by password and with System Owner permissions?
Of course you can uninstall from the safe mode. Disable the authorization in the Device Administrator first.

Step for booting in safe mode:


From any screen, press and hold the Power key.
Touch and hold Power off. Review the 'Reboot to safe mode' screen,' then tap OK. 
The device should restart in safe mode and 'Safe mode' will appear in the lower-left.
Uninstall the app that is causing a problem.