Tutorial: How to run Legacy and Chromium-based Edge simultaneously side by side Without Group Policy

1. Uninstall Chromium Edge either from Control panel or from Windows 10 settings => Apps

2. Go to Registry Editor by typing "regedit" in Windows 10 search

3. Navigate to: 

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft​

OR paste this in the address bar area of Registry editor

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft​

4. Right-click on "Microsoft" and create a new key

And name it "EdgeUpdate" (without quotes)

5. Then right-click on "EdgeUpdate", go to New and create a new DWord 32-bit and call it "Allowsxs" (without quotes)

Allowsxs

6. Set its value to 1

7. Exit Registry Editor

8. now go to www.microsoft.com/Edge to download Edge stable again. install it and after that you will be able to access both Legacy and new Edge from start menu or Windows 10 search.

Source:

https://docs.microsoft.com/en-us/deployedge/microsoft-edge-update-policies#allowsxs

This tutorial is for using only Registry editor, there is also another method to do this which is through Group Policy

https://docs.microsoft.com/en-au/deployedge/microsoft-edge-sysupdate-access-old-edge#how-to-enable-a-side-by-side-experience-with-both-versions-of-microsoft-edge

for that you also will need the policy files which you can get from here:

https://www.microsoft.com/en-us/edge/business/download