You can do this, remove the
MockVault file from the OS’s temp folder, launch the browser, create as many dummy accounts as you like (perhaps all with the same password so it’s easier to then login), close the browser, and finally make a backup of the new
MockVault file created.
Anytime you want a fresh start, just replace the mock file with your backup. You can also do this to keep some data you want as a base for your dev/tests activities while developing.