Sitecore 9 install error - You must remove all users with password before setting the containment property to NONE

When attempting to install a Sitecore 9 (update 1) instance the PowerShell installation script failed with the following error:

Install-SitecoreConfiguration : Command C:\Program Files\iis\Microsoft Web Deploy V3\msdeploy.exe returned a non-zero exit code - (-1)At C:\Install\Sitecore9.1\Install.ps1:42 char:1+ Install-SitecoreConfiguration @xconnectParams+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,Install-SitecoreConfiguration

Further up in the window it was traced back to the following source error:

Error: .Net SqlClient Data Provider: Msg 12809, Level 16, State 1, Line 5 You must remove all users with password before setting the containment property to NONE.

My deploy script had failed on a previous run (due to invalid SOLR base URL), however databases had been added to SQL. By removing the following 4 databases from SQL, the error above would no longer appear and Sitecore would install as expected.

1. [prefix]_MarketingAutomation
2. [prefix]_Messaging
3. [prefix]_Processing.Pools
4. [prefix]_ReferenceData

Where [prefix] is as configured in your installation script.