Unable to remove GUI applications from /nix/store using garbage collection

[ryullulala]

Description

I attempted to clean up /nix/store using both sudo nix-collect-garbage -d and nix-collect-garbage, but certain packages remain undeleted. The persistent packages are GUI applications such as Alacritty, Arc-Browser, Google Chrome...

Steps Taken

1. Removed the applications from Nix configuration and ran darwin-rebuild switch
2. sudo nix-collect-garbage -d
3. nix-collect-garbage
4. ls -la | grep "arc-browser"
   

Expected Behavior

The garbage collection commands should remove unused packages from /nix/store

Question

What is the proper way to remove these GUI applications from /nix/store?

[x6ufeng]

Well, as far as I know, the gui apps may need a reboot to finish the removal.

[ryullulala]

Well, as far as I know, the gui apps may need a reboot to finish the removal.

I've tried multiple times but it's not disappearing at all.

[DontEatOreo]

Usually when I run nix-collect-garabage -d I will run into an error like this:

deleting '/nix/store/1zdm48k9nv0sf4n5qmipfj1z5zwwyzxc-discord-0.0.324'
0 store paths deleted, 0.00 MiB freed
error: chmod '"/nix/store/1zdm48k9nv0sf4n5qmipfj1z5zwwyzxc-discord-0.0.324/Applications/Discord.app"': Operation not permitted

I get around it by just doing sudo nix store delete /nix/path/to/program

e.g:

$ sudo nix store delete /nix/store/1zdm48k9nv0sf4n5qmipfj1z5zwwyzxc-discord-0.0.324/Applications/Discord.app/
  /nix/store/1zdm48k9nv0sf4n5qmipfj1z5zwwyzxc-discord-0.0.324
[0.0 MiB DL]1 store paths deleted, 417.82 MiB freed

[maxRN]

I solved it by running nix-collect-garbage -d (NOTE: not running as root)
and then running sudo nix-collect-garbage --delete-older-than 5d (adjust the days as necessary).
The first step deletes old home-manager generations which keep these packages from being removed.

There is currently a "bug" which prevents nix from deleting old generations when running as root, see NixOS/nix#8508 and https://discourse.nixos.org/t/home-manager-and-garbage-collection/41715