Here are the steps. You may need to print this instructions unless you have another device to follow along as you will not be able to view this page as you do each step:
Turn off your computer, then hold power button while starting up until Options button appears. Click the button and continue, you may be asked to choose your startup drive.
- DISABLE SIP by following these steps
In the menu bar of the Recovery Mode, choose Utilities > Terminal.
Enter the command "csrutil disable", without quotes followed by the Return key
Quit Terminal by going to Terminal > Quit
Go to Apple menu and choose Restart
In the Utilities Folder there is an app called Terminal. Double click to open it.
Enter the following command and hit return. (Make sure there is a space on each side of "-")
sudo systemextensionsctl uninstall - com.avira.scanservice.systemextension
Quit Terminal by going to Terminal > Quit
Turn off your computer, then hold power button while starting up until Options button appears. Click the button and continue, you may be asked to choose your startup drive.
- ENABLE SIP by following these steps
In the menu bar of the Recovery Mode, choose Utilities > Terminal.
Enter the command "csrutil enable" without quotes and then the Return key.
Quit Terminal by going to Terminal > Quit
Let me know if there is any trouble along the way.