Hi MMelchert,

Thanks for reaching out here.  Although you can convert your sub-customers to a project, there's currently no option for undoing the process.  I'll be happy to provide other options so you can decide which one works for you.

The first way would be to delete the project and re-create it.  Another option would be to re-create your sub-customer by going to Sales > Customers > New.  Enter the Customer's name and add an identifier to the beginning or end of the name, such as an * for example, proceed to make them a sub-customer and then save.  The identifier will eliminate the notification that this customer already exists.

Feel free to reach back out if you have other questions.  We'd be glad to assist!