Is it possible to scale +5v : -5v AC to effectively 0:0 with a potentiometer?
Assumption: The requirement is for a controlled, deterministic attenuation. 

A complete attenuation to zero signal is impractical using a voltage divider. In essence, a zero signal would be the equivalent of disconnecting the input entirely, presenting a short-circuit at the output. The answer by gbarry covers this simply and excellently.

Other than this, an attenuator will typically attenuate the signal asymptotically - approaching zero but not quite getting there. 

This arrangement would get you approximately 100:1 attenuation (-40 dB), which might serve the intended purpose. 







simulate this circuit &ndash; Schematic created using CircuitLab

When the potentiometer is at the bottom position (zero Ohms) the output signal would be +/- 5 Volts at maximum input signal. When the pot is at the top position (100k Ohms) the output would be +/-0.05 Volts. Thus, an attenuation range of 100:1 is achieved. 

A voltage follower at the output is recommended, if the load to be driven is low impedance.

For the same -40 dB attenuation, an alternative is a precision attenuator such as described in this note.



If a greater attenuation is required, higher values of the potentiometer could be used, but at some point the resistive noise from extremely high pot resistance would smother the actual signal below usability. At that point, it would make sense to use an op-amp based attenuation circuit.

Alternatively, for high precision high attenuation, specialized ICs such as the LM1972 (-78 db attenuation, 7700:1) might be preferable. These are essentially single-chip digital potentiometer devices specialized for audio type signals.