I understand that you want to know how to remove all transactions before January 1, 2023, in QuickBooks Desktop (QBDT) 2023, @Finaco. Allow me to guide you through the process.

To do this, you can use the "Condense Data" feature in QBDT, which will delete unnecessary transactions and list entries, including those before a specific date. However, please keep in mind that this process is irreversible.

Before proceeding, please consult your accountant and technical support to ensure that this is the right solution for you. The Condense feature is recommended if you have a large data file, are approaching a list limit, or have recently upgraded your hardware. Here's how you can use it:

1. Go to the top navigation bar and select File.
2. Click on Utilities and choose Condense Data.
3. Select the option that suits your company best. The system will provide an approximate reduction in your file. Then, select Next. 
4. In the "Condense Data" window, select "Transactions before a specific date" and set the date range to "Before 1/1/2023".
   Please refer to the attach image below:
   
5. Follow the prompts to complete the process.

For in-depth information on Condensing data in QuickBooks Desktop, refer to this article in QuickBooks Desktop (QBDT): Use the Condense Data utility

Looking ahead, if you're interested in transferring your QuickBooks Desktop file to QuickBooks Online (QBO), check out this article: Condense your QuickBooks Desktop file for import to QuickBooks Online

Please let us know if you have any questions or if there's anything else I can help you with regarding condensing data in QBDT. Best regards.