I have been testing the accounts version of 1Password on my phone and wanted to revert back to my local vaults. The only way I could find to turn off the online vaults was to delete the app from my phone and then add the vaults back in from dropbox again. The sign out button was greyed out ?
1Password Version: Not Provided
Extension Version: Not Provided
OS Version: Not Provided
Sync Type: Not Provided
Sorry you had some trouble with that! I believe the sign out button will be grayed out if you're only signed into that one account and don't have any local vaults in the app on that device. Since you wanted to switch back to local vaults (and already had existing sync files in Dropbox), deleting and reinstalling the app was one way to do that. Going to 1Password > Settings > Advanced > Erase All 1Password Data would have done the same thing without needing to delete/reinstall the app. Alternately, you could have added your Dropbox vaults first (before signing out of the account) by going to 1Password > Settings > Vaults > Sync Additional Vault.
Did you add or edit any items while using your 1Password.com account? If so, those changes won't be in the vaults you sync from Dropbox. In that case, you can re-add your account, copy the new/updated items from the account vault(s) to your local vault(s), then sign out of the account again.
If you need more help with that or have any questions, please let us know! :)