Bulk Delete, or Bulk Copy + Paste into new Business File

In many tabs, there are batch operations (buttons available at the bottom of the page) that let you export, manipulate in a spreadsheet, and re-import. That feature might help. In cash accounts, there is the find and recode feature, which could help. See these Guides:

The 2nd Guide is for inventory, but the process is the same wherever it is available.

Also, don’t give up on the idea of starting from the present without recreating all past history. Regardless of how your position was determined, if you know it, you can set a start date and begin with opening balances.