Hi,
To change the AWS configuration you'll need to wipe the contents of the AltaVault (and cloud) to start over. From CLI issue these commands:
enable
configure terminal
no service enable
datastore format all
(respond 'Y' to wipe cache and cloud contents; this is a permanent action)
stats clear-all
logging files rotation force
At this point, you can use th UI Configure -> Cloud Settings Wizard to reconfigure the AWS configuration as needed to your liking.
Regrds,
Christopher