Hi  Lawrence,

Goto Settings / General Settings and enable the reset password option.

After logging in, to change your password, go to 'My Profile,' where you'll find the 'Change Password' option under action.

Hope it helps,
Kiran K

go to your terminal

write 

>sudo su postgres

>psql db_name

>update res_users set login='my_email', password='my_password' where id=your_user_id;