Uninstall Avira per their directions , then run etrecheck again to see what chaff it left...
Do what you can to delete or move enough files so you have at least 50 GB free space.
Clean up: Get Find Any File...
http://apps.tempel.org/FindAnyFile/index.php
Hold Option or alt key when selecting Find to Find All.
[Disabled] AVG AntiVirus - version 13.14.480 (AVG Technologies CZ, s.r.o.)
Application: Not found!
[Running] AdGuard Network Extension - version 2.10.0 (Adguard Software Limited)
Application: Not found!
Description: AdGuard Network Extension
[Running] Little Snitch Network Extension - version 6.0.4 (Objective Development Software GmbH)
Application: Not found!
Description: This extension is required for Little Snitch to be able to monitor and filter network traffic on your Mac.
[Running] Avira Scan Service - version 9.4.5 (Avira Operations GmbH & Co. KG)
Application: Not found!
Description: Provides the Antivirus Scans and Protections
Delete this file...
/Library/Application Support/Microsoft/MAU2.0/Microsoft AutoUpdate.app/Contents/Library/LaunchDaemons/com.microsoft.autoupdate.helper.plist
/Library/LaunchAgents/at.obdev.littlesnitch.agent.plist