Need to Add "Delete" option On discussion board

I need to add "Delete" option besides "Reply" option.

I was trying to modify thread.xsl to get the delete option on discussion board.

I need to modify the share point files ,so that it will get reflected on whole web app.

Because my app has more than 100 sites.

I can not add "Delete" option for these many sites manually.

Thats why i need to modify share point files.

Find the below screenshot to get my requirement.