They erase 'Dagh' (the stain/poet) in this manner, telling him to change his name because it has now become too old.

Dagh creates a brilliant wordplay around his own pen name, which literally means a 'stain' or 'scar'. While one usually scrubs away a stain to erase it, the beloved dismisses him with effortless cruelty, telling him his name is simply too outdated and needs changing. It captures the beloved's teasing indifference and the lover's tender melancholy at watching his entire identity be cast aside like an old habit.