There are 2 parts to the registry entries when you install Toad for DB2. The first part is the Toad registry entries, which are located at HKEY_LOCAL_MACHINE\SOFTWARE\QUEST SOFTWARE\Toad for DB2. The second part is the DB2 client registry entries which are installed by the DB2 v9 client merge modules that come with the Toad for DB2 installer. If you do not have any other DB2 clients installed on your machine, you can delete the whole HKEY_LOCAL_MACHINE\SOFTWARE\IBM\DB2. However, if you have other DB2 clients installed, only HKEY_LOCAL_MACHINE\SOFTWARE\IBM\DB2\InstalledCopies\ToadC30 can be deleted.
Toad only adds some file assocation entries in HKEY_CLASSES_ROOT, which will not hinder any functionalities.
However, the DB2 client Toad bundles may also have written some entries in HKEY_CLASSES_ROOT, since it was installed by IBM merge modules, you have to use the utility bat file from IBM to clean them up.
Make sure you do not have any DB2 clients installed on your machine other than Toad, otherwise, you will have to uninstall it first since this bat file will clean them all.
1. uninstall Toad
2. run db2unins.bat to clean up the registry
This bat file comes with IBM DB2 V9.x ESE.