Nod32 Uninstall problems.

Hi.

I uninstalled Nod32 some time ago and now use Kaspersky instead. I used the regular uninstall-application that came along with the program and everything went fine. But now (like 3 months later) when I use "Sysinternals Process Explorer 10.11" I find that Nod32's "Imon.dll" still resides in my system (C:\Windows\System32\imon.dll) and is being used by "Firefox.exe", "Svchost.exe" and "Miranda.exe".
I can´t delete the dll-file, I only get "Access denied". I have tried to unregister the dll-file with regsvr32.exe /u imon.dll but that won´t help either. I simply can´t get rid of the file safely. How can I delete the file safely and stop it from being used/loaded into the memory? I guess I can boot safemode and delete it but is it safe?

Regards // Matt