1. Clear your cookies and cache
If that doesn't resolve the issue, you can manually remove the saved username and password by following the steps below:

Google Chrome-
  1. Click the button at the top right of the browser with the three dots and choose Settings from that drop down menu
  2. Scroll down and click on Advanced
  3. Scroll down to the Passwords and Forms section and click on Manage Passwords
  4. Find the website and unwanted saved username in this list
  5. To the right of the username click on the three dots then click Remove
Microsoft Edge-
  1. Click the button at the top right of the browser with the three dots and choose Settings from that drop down menu
  2. Scroll down and click on View advanced settings
  3. Scroll down and click on Manage my saved passwords
  4. Click the X button next to any saved username you would like to delete