Hi,
goto run command in the start and type regedit. It takes you to the regestry keys file. In that file, expand the HKEY_Localmachine tree and locate software subtree. When u expand that,you will find the software. Rightclick it and select delete. Repeat the same procedure with the other trees too.
Hope this helps.If still u cannot delete, download microsoft blaster from ni ftp site and run the program.It leads you to your solution.
Chaitanya