No. TurboTax accounts cannot be combined or merged. Keep a record of how to access your "old" account(s) and use one of the accounts going forward.
SAVE YOUR TAX RETURN !
EVERY year before mid-October you should save a copy of your tax return as a pdf and print a copy of it for your records. That way you will not be searching online frantically when you need it for a lender, FAFSA forms, your next tax return, etc.
https://ttlc.intuit.com/questions/1900937-why-should-i-save-a-pdf-copy-of-my-return
https://ttlc.intuit.com/questions/1899779-what-s-the-difference-between-the-tax-data-file-and-the-pdf-file
https://ttlc.intuit.com/questions/1912466-how-do-i-save-my-return-as-a-pdf-in-the-turbotax-software-for-windows •
NOTE: TurboTax and the IRS save returns for seven years. Returns older than seven years are purged.