Why did polydectes want to kill perseus?

Polydectes, the king of Seriphos, wanted to kill Perseus because he was infatuated with Perseus's mother, Danaë, and wanted to remove her protective son from the picture. To achieve this, he devised a plan to send Perseus on a seemingly impossible quest to retrieve the head of Medusa, hoping that the dangerous task would lead to Perseus's demise. Polydectes underestimated Perseus's abilities, which ultimately led to his own downfall.