Problem with Xbox Avatar app...

I'm having the same problem. If Xbox 360 avatars are impossible to delete or replace without an Xbox 360, then what is the purpose of the Xbox Original Avatars app? ( https://www.microsoft.com/en-us/p/xbox-original-avatars/9nblgggz5qdq?activetab=pivot:overviewtab )

People can update an avatar, but it won't actually be updated anywhere?

There is an ‘Xbox Original Avatars’ app and a ‘Xbox Avatar Editor’ app

if you want to keep your 360 Avatar as is you can download the original avatars app and customize through there and then vis versa with the Xbox one version if you would like an updated/new look for your Avatar. Both can be found througu the microsoft store
for free or through games and apps search bar.

Goodluck!

Also have this problem. No error messages, Avatar Editor just tells me to go to the games app. Uninstalled the games app to try to edit avatar but it still told me to go to the games app. So annoying...

That app does have the 360 avatars. That would be the only way. Keep in mind there are 2 apps. One is just the Avatar Editor which does not have the 360 avatars. The Xbox Original Avatars app does have them.

There are two differents apps - one for the old avatars, one for the new avatars.

You will have to install and use the old app, "Xbox Original Avatars".