Most likely to succeed is to click the Close button [X] on that Task Pane's
title bar, or you might prefer to use a different View. What options you
have will vary somewhat depending on which version of the program you're
using, but you neglected to mention that.
Tools, Options, View tab, at the bottom "Outline and Normal options" reduce
the Style area width to zero. This is for 2003 and prior, for 2007
instructions will be slightly different.
Hope this helps
DeanH