When the application is uninstalled successfully, hopefully, you will be able to stop avast browser opening on startup issue.

Now check the box parallel to “Also delete your browsing data” and click on the “Uninstall” button.

Launch your favorite browser and download the Avast uninstaller utility from its official website.

Now click on the “Uninstall” button associated with the browser and follow the on-screen instructions to remove the browser completely from your computer.From the right side of the window, locate and select the “Avast Secure Browser” option.Right-click on the “Windows” icon and click on the “Apps and Features” option from the pop-up menu.Follow the on-screen instructions to complete the uninstallation process and check whether now you’re able to stop avast browser opening on startup.Now right-click on the “Avast Secure Browser” in the list of applications installed on your PC, and click on the “Uninstall” option.Now type “appwiz.cpl” command in the text field of the run box and hit the “Enter” key on the keyboard.Right-click on the “Windows” icon and click on the “Run” option from the pop-up menu.Method 3: Uninstall the Browser Through Control Panel: Now save the settings and reboot your computer to make sure that this browser doesn’t open when your computer starts.Scroll down to the bottom of the screen and disable the toggle button parallel to the “Launch Avast Secure browser automatically when your computer starts” option.Now locate and select “Settings” from the pop-up menu to modify the startup settings of the browser.Launch the Avast secure browser and click on the “Menu” icon located on the top-right corner of the screen.Now reboot your system and hopefully, now you’d be able to stop avast browser opening on startup.Under the “Startup” tab, select the process related to “Avast Browser” and then click on the “Disable” button to prevent it from starting during the startup process.Right-click on the “Windows” icon and type the “Task Manager” in the Search Box.

Workaround: Method 1: Disable the application in Task manager

Disable avast browser at startup