Note: Wordpress version 2.6.2

Step 1. Download wordpress-dashboard-editor plugin (here).
Step 2. Unzip and upload to plugin folder (/wp-content/plugin/).
Step 3. Active plugin.
Step 4. Open dashboard management.
Step 5. Select checkbox for remove (hide) them all and save :p finish !

Reference: Tips on speeding up WordPress Admins Dashboard (Wordpress-blog.nl)