As we know, we can make the overtime and billable work disapear, but not the planned work :( ( god knows why). Anyway here is the instruction on how you can hide the planned column in the Project Server 2007 timesheets:
Use the following procedure to hide the ‘Planned’ work section displayed by default in the my timesheet input screen
1. On the Application server, open the CSS file named [pwastyle.css] in the SharePoint 12 hive structure.
Should be something like C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\PWA\STYLES
2. Locate the class named [XmlGridPlannedWork]. Within the class, add the following highlighted code to the class and save the file:
Easy Peezey. Planned work has been banished to the Project Server abyss and is no longer visible.
Dont you just love great developers :)