Removing the text is a simple call to remove if you don't need this Text instance again:
Code:
#display text
Text=viz.addText3D('Hello world', pos,color .....)
#remove text
Text.remove()
If you want to hide/show the same text multiple times us this:
Code:
#create/display text
Text=viz.addText3D('Hello world', pos,color .....)
#toggle visibility with these
Text.visible(viz.OFF)
Text.visible(viz.ON)