How to replace a toothbrush head

Securely hold the toothbrush handle with one hand, then firmly pull the toothbrush head with another hand.
(Fig.1)

Clean the toothbrush handle including the connector pin.

Securely hold the toothbrush handle with one hand, then firmly press the toothbrush head down with another hand leaving about 1mm space between the handle and the head.
(Fig.2)