If the IRS is rejecting your return because their website says you already filed, then you have "NO CHOICE" but to print, sign and mail your return to the IRS. Once the IRS computers have an SSN marked/labeled as claimed/filed, *NOTHING* will change that for the current tax filing year.
Now if you did "IN FACT" file your return and it was accepted by the IRS, you're done for the 2019 tax filing season. If you need to change something on you already filed and accepted return, you'll have to file an amended return. An amended return can not be e-filed. The IRS says so. You have to print it, sign it (both the 1040 and 1040X) and mail it to the IRS.
