I need my 2018 AGI to e-file. For 2018, I used the TurboTax software and have the tax2018 file. I deleted the 2018 TurboTax software, can I open the tax2018 file somehow?

In order to open the .tax2018 file, you would need to re-install the 2018 TurboTax program on your computer.

Your better option might be to get the 2018 AGI from an IRS transcript of your 2018 return.  Use this link to request a Tax Return Transcript:  IRS Get Transcript

@mnich55