A little more information would have been helpful - Avast Program, Operating System ?
This information assumes Avast Premium and Windows OS.
1. Cancelling automatic renewal of the Avast subscription - See
https://support.avast.com/en-en/article/35.
2. Is this not the same as the above ?
3. Avast can be uninstalled in the same way as other programs - Control Panel > Programs > Uninstall a program > find the avast program that you have and select Uninstall.
