The only way to downgrade after upgrading is to clear and start over, which obviously cannot be done in a paid-for or already-filed return.
You'll need to phone TurboTax Support and tell them exactly what happened. If you are lucky, they may just unlock the prior returns for you without a fee. But in any case, you should not have to pay that much to unlock returns. PLUS is 19.99, while Self-Employed Edition is 119.99. So they should work with you in some fashion.
Or if a 2017 tax return transcript will suit your purposes, you may be able to immediately download a 2017 return transcript at the IRS
website at the link below. If you don't qualify to open a free IRS
account there, you can order one to come by postal mail, which normally
takes 5-10 calendar days.
http://www.irs.gov/Individuals/Get-Transcript
Here's how to phone TurboTax Support. Since you are currently in Self-Employed, it qualifies for phone privileges. So in order to get to Support, indicate that is your product.
They are open tomorrow Saturday 5AM-5PM Pacific (8AM-8PM Eastern.) Then Mon-Fri after that.
