You can uninstall the newest version of edge in Windows. The newer edge is chromium based and it seems you can remove it now. However the previous version of edge that was built into windows could not be removed with traditional methods.
You can’t uninstall edge without breaking things such as start menu search, widgets, bing AI, The upcoming co-pilot, and a lot more. I’ve personally been battling for people by creating MSEdgeRedirect, but there’s been two to three attempts to break the project so far.
I should have mentioned I was talking specifically about Windows 10 LTSC version. I have that on one machine only for my fiancée to use, I was definitely able to uninstall edge on that so that Firefox would be the only option.