Can I delete all transactions and start over in quickbooks self employed

Welcome to the Community, @clboudreaux14. Yes, you can delete imported transactions so you can start fresh. Please note that you can't undo this action. 

Here's how: 

1. In the Gear icon, select Imports.
2. Choose the bank name with imported .CSV files.
3. Once you see the list of imported data, click the trash icon to delete all the imported transactions with that file.

Here's an article that can help you connect your bank and credit card accounts to QuickBooks Self-Employed so your recent transactions will be downloaded automatically. It also contains a link to categorize transactions. 

Feel free to message again if you need additional help. We're always here to further assist