dbca cant remove database cleanly when I ran dbca as administrator under windows server 2008R2 is used to delete the database completely ( database folder, control files, datafies, redo logs, then remove all related windows services to the database), but recently I noticed when I use it I found the services still exist as well as the trace (still generated), mail folder inside oradata still exist, as well as I can try to remove it countless time.

DB trace:

2015-02-16 15:31:48.434: [  OCRMSG]prom_waitconnect: CONN NOT ESTABLISHED (0,29,1,2)
2015-02-16 15:31:48.439: [  OCRMSG]GIPC error [29] msg [gipcretConnectionRefused]
2015-02-16 15:31:48.439: [  OCRMSG]prom_connect: error while waiting for connection complete [24]
2015-02-16 15:31:48.440: [ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\olr cannot be opened. error 2

*** 2015-02-16 15:31:50.494

2015-02-16 15:31:50.494: [  OCRMSG]prom_waitconnect: CONN NOT ESTABLISHED (0,29,1,2)
2015-02-16 15:31:50.494: [  OCRMSG]GIPC error [29] msg [gipcretConnectionRefused]
2015-02-16 15:31:50.494: [  OCRMSG]prom_connect: error while waiting for connection complete [24]
2015-02-16 15:31:50.494: [ default]ut_read_reg:2:ocr registry key SOFTWARE\Oracle\olr cannot be opened. error 2


Any suggestion to fix this issue?
When you install Oracle there are a set of registry entries under hkey_local_machine, software, oracle. If you don't have the registry, and don't want the Oracle home, then you can just delete the directories. There is an Oracle directory under program files, which stores your Oracle Inventory, and your Oracle Home where ever you put that.