This is my first message. I’m sorry if I sound anything but technical, but I have spent hours and hours trying to uninstall Avast(free) so I can install software that my internet provider is offering. Even had the tech from IP try and he said Avast will have to do it. How do I find someone who even cares?!
Read the instructions before You start
http://www.avast.com/uninstall-utility
By software i guess You mean another antivirus?
Did you use the regular Windows add remove programs uninstall ?
What have you tried in uninstalling and what errors if any were displayed ?
Even had the tech from IP try and he said Avast will have to do it.
That doesn’t speak well for the competency of the IP’s technician. 
Bob ;D
Use tech instead of the real Tech ;D