Resolve Xbox game account association?

I bought an Xbox incl. Forza Horizon 4 and linked the game to my Xbox Account. Now I want to sell the Xbox again and would like to know if I can separate the game key from my account, and then sell it.

Friendly greetings

It does not work. Digital purchases on the Xbox are inevitably connected to your Xbox Live Accoumt. You would have to sell your account (credentials). Although not allowed, but who cares.

All games you bought digitally will remain in your Xbox profile forever. But see it positively. Games like Forza Horizon 4 are Xbox Play Anywhere games. Means that if you buy the game on Xbox, you can continue to gamble on the Windows 10 PC. The PC version is then also "bought". Also plays in other games, such as Sea of Thieves, Halo Wars 1 Remaster, Halo Wars 2 …