Article: Hiding Tasks in Snapshots
While in the "Tasks" tab on your project, click in the column headers, choose "Add Column", Click on "Advanced" then select "Restricted."
This column is reserved for Professional and Enterprise Edition users and relates directly to the Publish Snapshot feature.
For any tasks that you don't want to display in your next Snapshot, simply select "Yes" in the Restricted column.
The next time that you create a Snapshot, those tasks marked as "Restricted" will not be included in the Snapshot.
You can also set up your preferences on a template if you know you want to create your Snapshots in a certain manner most of the time, e.g. only show all Milestones. If you set up the restriction on your template, any projects you create from that template will automatically inherit those settings. You would then need to only update any newly added.