1. Goto Start -> Run
2. Type cmd and pres Enter button.
3. Type D: and press enter button.
4. Type "attrib -s -h -r autorun.inf" without quotes and press Enter button.
5. Type "del autorun.inf" without quotes and press Enter button.
Now you will find your autorun.inf folder is a normal folder and you can delete it normally by using the del button to throw it in recycle bin or using Shift+Del buttons to delete it permanently.I think it must work well in your computers.
You can delete manually using 7zip file manager as it shows the hidden files also, and there is way to disable autorun features.. But the best thing is you have a working anti virus...
V can also try- go to task manager, check running applications, choose autorun.inf, click end process., now u can delete autorun.inf files easily from ur system..