Hello Sigrid,

in your override, you can add, at the beginning of the file:

unset($this->filters['sorting']['brand']);

unset($this->filters['sorting']['rbrand']);

The sorting key is set to:

[
  "" => "Sort Product by"
  "pname" => "Name (A - Z)"
  "rpname" => "Name (Z - A)"
  "min_price" => "Price (Low > High)"
  "rmin_price" => "Price (High > Low)"
  "sku" => "SKU (A - Z)"
  "rsku" => "SKU (Z - A)"
  "brand" => "Brand (A-Z)"
  "rbrand" => "Brand (Z-A)"
]