I'd like to switch back from qb online to self-employed. How do I do this?

QBSE is a stand alone product. You can only migrate data from your bank.

https://quickbooks.grsm.io/UK-SE

Hello Coffeexakeplay-g, 

Welcome to the Community page, 

So it would be just a case of taking out a qbse account under a different email address and connecting your bank account in it so you can us that going forward and then just be a case of canceling the small business online account you have with us.