Hi Jun,
I face the same problem in Suse Linux.
Most of our directories were deleted after reboot ( Thanks to VM guys and there settings! ) , so we had to reinstall.
It could not let me uninstall , as there was no kernel and wanted the same instance numbers 00 and 01. I looked more in sapinst.log.
I found it picked instances from /usr/sap/sapservices file which provides environment variables.
A) Took a deleted it (cp file_old of this file) ( or delete entries related to your SID if other SID's are there )
B) After doing this - > uninstallation did not ask for kernel/anything - It unistalled clean
( Here there is one step - deleting from system registry - I think thats what you did in Windows )
Then I retried installation - I took 00 and 01
Regards,