TurboTax accounts cannot be deleted or combined. Choose one to use consistently going forward and abandon the other ones---but keep a record of how to access them "just in case"---any returns in those accounts are stored for seven years.
If you would like to compare your results using Married Filing Jointly with Married Filing Separately, you can use TurboTax Online to test different scenarios before deciding to file jointly or separately. Click here for more information from TurboTax on how to decide which filing status to choose.
Depending on other factors, it may still be better to file jointly. If you live in a community property state (Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington, and Wisconsin), you will need to split your community income evenly even if filing separately; the rules vary by state. Also, some tax benefits aren't available for Separate filing status.
Click here for tax tips for community property states.