I managed to make it work using the setup macro as following:

  setup do
    # Get the pids of all currently alive processes
    accounts_used_pids =
      DynamicSupervisor.which_children(Account.Cache)
      |> Stream.map(fn entry ->
        case entry do
          {_, pid, :worker, [Account.Server]} -> pid
          _ -> nil
        end
      end)
      |> Enum.filter(fn ele -> ele !== nil end)
    
    # Terminate all processes
    Enum.each(accounts_used_pids, &Process.exit(&1, :clean_up))
    
    # Reset the "database"
    File.rm_rf(Account.Database.folder_path())
    File.mkdir_p!(Account.Database.folder_path())

    :ok
  end

The setup macro runs the code inside it after each test case. So I clean up the database and terminate all processes related to the account, after every test case.

It might not be the optimal solution, but work for me! Thank you so much for the help!