Can I un-file my taxes

the return at this point can't be recalled. the IRS won't open e-filing until 2/12/2021. so you'll have to wait. if your return is rejected you can fix it and resubmit.  if it is accepted you'll have to wait until it is fully processed and then file an amended return 

Unfortunately, no. Imagine that you have dropped it in the mailbox and the postman has collected it. Once it is filed, it is gone. The exception, as noted above, is if it rejects due to incorrect information. The IRS kicks it back and it is not considered to have been filed. It is best to wait until you have all your information available to file.