I have installed the free Avast antivirus but I don't know why I installed the Avast Secure Browser, can I uninstall the browser and continue with the Antivirus?

Avast Secure Browser Avast Secure Browser for Windows
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It isn’t clear what it is that you don’t want - if it is the Avast Secure Browser for Windows.
This is a Secure Browser - that you physically have to install.