How to uninstall oracle 10g from windows xp?

First you have to remove all the oracle products by using oracle universal installer

goto start button  -> programs -> oracle-oraDb10g_home1 -> oracle installation products ->

click on the universal installer. you will get welcome screen, click on the deinstall products

to remove the oracle products. after uninstall the products.

Now you have to remove all  the remaining oracle products manually

run this command regedit.exe. you will get registry editor. 

find related to oracle by using ctrl+f and remove all you find related to oracle, 

do this again and again untill you get nosearch .

after completing this, reboot your system.