No need to "cancel"---just abandon the return. Nothing will happen to it. No one else has access and it will not be filed. If you did not register, pay or file, you can try to clear it.
CLEAR AND START OVER. (or....just clear it and do not start over)
https://ttlc.intuit.com/questions/2586254-how-do-i-clear-and-start-over
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**