One way to Grey out a Voice

1) Copy the file, open the copy
2) Make sure Selection Filter is enabled ( View -> Selection filter)
3) Click F6 to open the selection filter.
4) Filter for the voice you want to remove
a. Click on All and
b. then on the voice you want to change (Say Voice 2). It should be the only item in the filter.
c. Then select all of the measures
d. Go to properties and select color
e. Pick a fainter color (whiter shade of pale)
f. Go back to filter and select ALL to make sure you can make normal selections.