Percent complete can be entered by a manager or a tracker. Percent complete can be entered independently of actual times.
To enter a percent complete value for an entire subtree, double click on the Percent Complete column for the project at the root of the subtree:
the selection dialog shown below appears.
click the checkboxes of the projects you wish to change
select the desired value from the Percent Complete drop-down list and click on the Set property for selected projects button
click the Save changes button to save your edits.