How do I change my username on intuit to match my username for quick books self employed if it says that username is already in use (on quick books)?

Login to your TurboTax account

Go to Intuit Account in the black column on the left

Edit 

It wont let me edit my username to the same one I use for quickbooks because it says it is already taken

Then call customer service to join the accounts, (800) 446-8848