1]
Change the boot.ini file so it won’t load

2]
You will be surprised if you know how much rubbish/malware there can be on a system.
I’ve seen systems with over 40(!) types of malware

3]
You did install it willingly.
If you didn’t wanted GrimeFighter, you should have done a custom installation or removed it after installing avast.

4]
Don’t blame avast for your mistakes/lack of knowledge.

GrimeFighter has been stopped around 6(!) months ago.