In QBDT versions, you simply create a new company file.  You can copy lists to the new company if needed.

Resolution for 'all data issue: 'I want to delete everything, all data, companies etc., and start fresh.How do I do that? Thanks' available: Yes.

The all data 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 all data issue yourself by looking for a resolution described in the article. If it is a complex all data issue or you are unable to solve the issue, you may contact us by clicking here or by using other all data support options.

For more information about resolving issues related to all data in Quickbooks/QBO or to get support for the issue 'I want to delete everything, all data, companies etc., and start fresh.How do I do that? Thanks', click the link below: