To hide styles in Word 2007: In the Styles pane (Ctrl+Alt+Shift+S), click
the Manage Styles button. On the Recommend tab, select a style that you want
to hide. Under "Set whether style shows..." click the Hide button. Repeat
for any additional styles that you want to hide. To transfer the setting to
the attached template, click "New documents based on this template" before
clicking OK.
Note that the above procedure only controls the display of styles. If you
want to prevent users from using certain styles, use document protection
instead: On the Review tab, click Protect Document, and then click Restrict
Formatting and Editing. In the task pane, click "Limit formatting to a
selection of styles" and click Settings. Click to remove the check marks
from the styles that you want to restrict. When you are done, click OK. Then
click the Yes, Start Enforcing Protection button in the task pane.
You cannot restrict the use of the Normal style, but you can hide it (as
explained in the first paragraph).