The concept of a clean boot was introduced in WM 5.0. A clean boot will cause the persistent storage area to be erased. This is the only method of erasing the persistent storage area.  The concept of clean boot does not exist in WM2003.

Clean boot procedure  for the MC9090:
1. Copy "CleanPS.bin" and "pkgs.lst"
(Found on CD at NSTL Submission 11-28-05\a3 Core
Feature Applications\Clean Boot files) to the \Temp
directory of the mobile hand-held device (or root
directory of storage card) through ActiveSync
2. While the device is on, partially eject the battery (press
silver buttons located on the lower-hand side of
the device).
3. Simultaneously press and release the red power and
yellow trigger button.
4. Insert the battery and hold trigger button.
5. Wait 4 seconds and release trigger.
6. Mobile hand-held device must have AC power to
complete procedure.
If AC Power is not present the screen will display:
"No AC power is detected. Image updates require AC
power.  Please plug in AC power"
"WARNING: Removing AC power during updates may
render unit inoperable.”
If AC Power is present then the UPDATE screen will appear.

You can load the necessary files from here:

support.symbol.com