You can change the password of your mailbox at your online Control Panel -> Mail Manager section.
Please refer to the following article on this matter:
Control Panel -> Mail Manager -> Change email account password
No setup fees. Minimum contract period for shared hosting services - 12 months. Full prepayment for the contract period. 100-day money-back guarantee. No automatic renewal. Fees for domain registrations and SSL certificates cannot be refunded in case of an early contract termination.