No matter what I try, I can’t uninstall Avast. The moment I installed it and rebooted everything went wrong. I can’t access Internet and most programs. My computer is now useless - I’m using a relative’s right now. I believe it’s because I didn’t uninstall AVG first. I’ve tried EVERYTHING!
I downloaded the uninstall utility to my flash drive, but my computer won’t let me access it. I’ve tried getting to the file multiple ways: Search won’t work, Control Panel’s Add/Remove Programs is mysteriously blank, I can access My Documents, but not My Computer (to get to C Drive where the program folder is), Internet browser just sits in a perpetual state of loading, etc. It’s like it’s deliberately preventing me from getting to the file to remove it (like something out of a bad AI movie- “I’m sorry, but I cannot allow you to delete me.”)!
What can I do? Turning off either AVG or Avast does nothing. I’m stuck. 
Thank you. Once I managed to get into safe mode, I was able to uninstall through Add/Remove Programs. Whew! I’m so relieved. I’m replying from my now workable computer. Thanks.