thank you for that. My problem was that my finger slipped during a login so instead of typing Username <tab> password, I typed Username <Caps Lock> password, so as soon as I would try to login it would display my full username and password on the dropdown. I originally figured it was in the browser, but since the Diskstation is on Chrome's list of "Don't cache passwords for this device" and I didn't see it anywhere, I gave up. Then I checked in my Google account itself (which has other login info) and it wasn't there either. It was also showing up on all the machines that I login from which I why I started to think it was cached on the synology instead. Your comment made me dig into Chrome again, and I was able to clear it by going to: Chrome, settings, clear browsing data, autofill form data.
Thank you for the help.