I don't think the Top Package wording on the Actor is something you can
remove. It will show up if you have either a Collaboration, Sequence,
Activity, or Statechart diagram.
In Model Explorer if you right-click on Top Package, select New, and select
one of the other UML Diagrams, then drop the Actor shape onto the page the
Top Package won't be there in the shape name. Since you're using an Actor
you'd probably want to inserte a Use Case diagram.
Aaron Rykhus, MCP, MCDST
Online Support Engineer