You should start a new return for yourself and not transfer from a Joint return. If you are using the Online version you need to set up a new account. You can not remove a spouse or switch the order of names. Then when you fill out your name, etc. you pick Married and not filing together with your spouse. You will have to enter their name and ssn on your return. And if one person itemizes deductions then the other one must itemize too, even if it's less than the standard deduction, even if it is ZERO! And filing MFS has other special rules.