Derogatory language usage in community app forum

One of the residents took to forum on the allegations he heard were made on him and used the following languga ein his thread, "
I would like to share a Telugu quote here to show the stupid's mindset,  " Memu chesthe Samsaram miru chesthe Vyabhicharam" 

We have requested the resident to delete the thread, but, he has rejected to do so

What would be an appropriate action to ensure decorum is maintained in the forum?