Force delete certain file

I have a program continously reappearing in my system.
Its not a virus, its a new launcher “addon” from a game and im unable to disable it.

Does avast have a function what lets me flag that file as a virus and delete it continously whenever it reappears?

No and that would be foolish if it is not malware.

If it loads at boot-time, remove the key for it from the registry.

Its not a virus, its a new launcher "addon" from a game and im unable to disable it.
Others may have had same problem. Have you done a "how to remove xxxxxx" google search?

The aplications simply readds itself to the registry even after multiple deletes.
I have tried to disable this “feature” from their own launcher, quarantine it, disable it with ccleaner, set the whole folder to read-only after deleting the file.
It reappears after launching the game, thats why i search for a way to auto delete it after closing the game.

Sounds like it is either created or downloaded if you start the game.
If it is downloaded, perhaps you can block the download in the hosts file or firewall.
If it is created, there is nothing you can do about it unless the game has a switch that can do so.

Anyway, this has nothing to do with avast.
Ask the developer of the game.