How can I delete the appearance stream for a Line annotation?

Q: How can I delete the appearance stream for the Line? We have a
requirement to allow the user to delete the line annotations.
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A:

You can remove an annotation from the page using
page.AnnotRemove(myannot) method.
If you just want to erase the annotation appearance without removing
the actual annotation use the following line:
  myannot.GetSDFObj().Erase("AP");