How to desactivate a Symbol

There is a relatively new option to have the contents of a symbol back into the main stage called "Break Apart Symbol to Layers". The option will preserve layers, frames, tweens and position.

Select the symbol, right-click and choose it from the contextual menu:

copy all its layer/frames and paste on the main timeline.  be careful doing this, and be quick to use the undo to reverse undesirable outcomes.

first save your fla with a version number appended.  click the first frame in the top layer and shfit click the last frame in the bottom layer to select all the layers/frames. right click over the selected and click copy.

to your main timeline and create a new layer and select the first frame/keyframe, right click, click paste.  make adjustments and when you think it's ok, save with an increased version number.