I can't sign in on Dropbox Passwords; it gives me a white screen

You should be able to unlink the Dropbox Passwords app from your devices using the Dropbox settings page for your account.

To do this, navigate to this page and scroll down to the section "View Dropbox content"

You will see entries for "DB Passwords Android", "DB Passwords iOS and Mac" and "DB Passwords Windows", depending on how many different devices you have setup Passwords on. 

From there, you can click on an entry, and select "Disconnect" to unlink your Dropbox Passwords account from that device

If you are planning to remove or unlink Dropbox Passwords on all of your devices, please ensure that you have printed or saved your recovery words beforehand, as otherwise you will not be able to gain access to your Passwords account again.

Let me know how it goes anonymous 

@ Walter, At this page, Dropbox connected app(photo attached), there is one connected app. But the error still occurs(photo attached). What should I do for next step? 

Hi anonymous, what happens if you tap 'I don't have my other device'?

1. Hi Jay , If I tap, 12 recovery words appear. I know that words.This is not my problem. I'll show the details of my problem(attach photo). In basic plan I can't sign in Dropbox password both mobile and browser extension. It stops at white screen( attached photo). After upgrading plan I can sign in. It says more than 3 devices( attached photo). There are 3 devices which are highlighted ( attached photo). These devices are only one device not 3. Why this happens? In Dropbox account there is only one connected app. I tried after unlinking app first before sign in Dropbox password browser extension the error still occurs . I only want to know how to unlik these highlighted devices. I don't find anything the possible ways.  

Assuming you have printed out your recovery words, are you certain you've completely removed the Dropbox Passwords app from the Dropbox site in your last image?