So I made a pretty stupid mistake and saved and closed out of a session with a tremolo effect on some vocal tracks that I really don’t like. I’m under the impression that I cannot remove the effect after a save and a close-out (but please correct me if I’m wrong about that), so is there any way to jerry-rig the tremolo effect out? The tremolo settings I used were the following: Waveform type: sine, starting phase: 0, wet level: 40%, Frequency: 4.00Hz. Windows version 7. Audacity 2.1.0. Thanks.
You can substantially reduce the effect quite easily. Use the same settings, but with the phase shifted by 180 degrees. So for your initial settings of:
Waveform type: sine, starting phase: 0, wet level: 40%, Frequency: 4.00Hz
you will need to apply the effect with settings of:
Waveform type: sine, starting phase: 180, wet level: 40%, Frequency: 4.00Hz
The result will be a bit quieter than the original, which you can correct by amplifying by 4 dB.
The result will not be perfect, but hopefully good enough (and a good demonstration of why backups are so highly recommended 
)
Thank you!