Forgot Username and Password

I set up Home Assistant months ago on my Synology NAS. I couldn’t get it to work properly so uninstalled it. I have now decided to give it another go but when installed it asks for my username and password and there is no way to reset this. Can someone explain to me in very simple terms how to reset/ retrieve my username and password. I am not an IT tech minded person and find the user guides very confusing.

Thanks Nathan. I have tried to understand that all afternoon and it means nothing to someone with little IT knowledge