This appears to be a bug. From main .odb screen go to menu Edit->Database->Properties...
you will see Password required
is selected. You can remove the selection and save but it never gets cleared no matter what. That is the bug.
You can fix with an edit to a file in the .odb. Best to have a copy of the .odb in case you mess something up in the process. It’s simple but best be safe. Open the .odb with an archive program. Then open the content.xml
file with a text editor. In the file you will find the following item:
is-password-required="true"
Change to:
is-password-required="false"
Save the file and the content of the .odb and then you should not have the popup anymore.