You can use the Condense Data Utility in QuickBooks Desktop (In the menu bar, click File, then Utilities and then Condense Data) to condense company file data.

To do this task:

1. In the menu bar, select File and then Utilities and then Condense Data.
2. In the first window of the wizard, select Transactions before a specific date and enter the appropriate date.
3. Put a checkmark in the checkbox labeled: Optional: Create a report showing which transactions cannot be removed.
4. Click Next and select the radio button Create one summary journal entry (recommended).
5. Click Next and select the radio button Summarize inventory transactions (recommended).
6. Click Next and select the transaction groups you wish to be removed.
7. Click Next and select the unused list entries you wish to be removed.
8. Click Next and click the Begin Condense button. BIG NOTE This does not start the Condense: it starts the report.

Few other helpful tips before handling this task and also before converting to QBO:

• Complete backup of your QuickBooks company file
• Update QuickBooks (Help menu > Update QuickBooks)
• Verify and Rebuild Data (File menu > Utilities > Verify and Rebuild Data)
  (do it a couple of times if it’s huge or old file)