Windows still doesn't allow uninstalling the built-in Edge browser, not even in the Insider fast ring build 18970. you can however use this powershell method to somehow uninstall it. i say somehow because the install files will still be in your system and another powershell command can reinstall it.
so open the PowerShell. Type PowerShell in the Search bar.Right-click and select Run as Administrator. Type the following command and hit Enter Get-AppxPackage
This will show you a list of all installed app. Look for Microsoft.MicrosoftEdge. Copy (Ctrl + C ) or write down the PackageFullName. Type following command with package name in it and press Enter. Get-AppxPackage Microsoft.MicrosoftEdge_20.10240.16384.0_neutral__8wekyb3d8bbwe | Remove-AppxPackage