How to remove Win XP SP3 manually

there are 3 method u can use. usually you can just remove it from control panel. but if there is no uninstall button, u can easily use other method (in this case use method 2)

Method 1:
Use the "Add or Remove Programs" item in Control Panel
Click Start, and then click Run.
Copy and then paste the following command in the Open box, and then press ENTER:
appwiz.cpl
Click to select the Show Updates check box.
Click Windows XP Service Pack 3, and then click Remove.
Click Finish to restart the computer after the removal process is complete.

Method 2:
Use the hidden $NtServicePackUninstall$ folder
Click Start, click Run, type c:\windows\$NtServicePackUninstall$\spuninst\spuninst.exe in the Open box, and then click OK.
When the Windows XP Service Pack 3 Removal Wizard starts, click Next.
Follow the instructions on the screen to remove Windows XP SP3.

Method 3:
Use the System Restore process
Note Before you use System Restore, make sure that you have restarted the computer at least one time after you installed Windows XP SP3. By restarting the computer, you allow for any remaining servicing processes to finish.
Click Start, and then click Run.
Copy and then paste the following command in the Open box, and then press ENTER:
%systemroot%\System32\restore\rstrui.exe
Click Restore my computer to an earlier time, and then click Next.
Click the date on which you installed Windows XP SP3, and then click Installed Window XP Service Pack 3 in the Restore Point box.
Click Next, and then follow the instructions on the screen to remove Windows XP SP3.

source: http://support.microsoft.com

bacteria comment: there is always other method to use..