No, you don’t have to „sync“ the password manually or delete encrypted files in your google drive. Just let the sync tool of google do its job . Means: if you change your password, the Masterkey file changes and this will be synced via the google client. if the sync is done, you can open the vault eg with the android app with the new password. There is no change of the encrypted files, so if you only change your password, the sync will process very fast. You might not recognise it.
In case of you have chosen a weak password initially and want to change the „strength“ of the encryption: please read this.