You will need to log into DirectAdmin and the log in details for DirectAdmin are included in the service activation email for your hosting package.
Once logged into DirectAdmin click on the icon on the top right to open DirectAdmins tools
Use the search bar to search for Softaculous Auto Installer and then click on Softaculous Auto Installer
Click on the WordPress manager icon
Click on Manage Users
Select the user you would like to change the Password for, put in the new password and then click Save
