How to bulk update existing path alias after changing the URL alias pattern? How to bulk update existing URL alias?

I have Path auto module add path alias to URLs. I have changed the URL alias pattern. Now I want to update the pattern of old URLs also.

How can I achieve this?
it works only to URL which does not have path alias – Vamsi


Then first go to /admin/config/search/path/delete_bulk and delete the aliases 
in question. 

Then update /admin/config/search/path/update_bulk