You cannot, QBO has no backup process other than the universal backups they make in case of server failure, etc.  If you are within the first 60 days of your file creation you could wipe all information and start over.

Resolution for 'backup information issue: 'I want to upload bank transactions for first time. How can I backup information just in case I have to reverse the process.' available: Yes.

The backup information issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the backup information issue yourself by looking for a resolution described in the article. If it is a complex backup information issue or you are unable to solve the issue, you may contact us by clicking here or by using other backup information support options.

For more information about resolving issues related to backup information in Quickbooks/QBO or to get support for the issue 'I want to upload bank transactions for first time. How can I backup information just in case I have to reverse the process.', click the link below: