Hi Pesk92,
First, the paths should have forward slashes and second you don’t place the full path, but the relative path. The example above would be:
../../../Engine/Content/Tutorial/
../../../Engine/Content/MobileResources/
../../../Engine/Content/MapTemplates/
../../../Engine/Content/Maps/
../../../Engine/Content/EngineSounds/
../../../Engine/Content/EngineResources/
../../../Engine/Content/EngineMaterials/
../../../Engine/Content/EngineDebugMaterials/
../../../Engine/Content/EngineDamageTypes/
../../../Engine/Content/EditorResources/
../../../Engine/Content/EditorMeshes/ColorCalibrator/
You will need to experiment with which files you may safely remove, but I’d recommend leaving EngineMaterials at least; at minimum it will need WorldGridMaterial.uasset. You may list individual files if needed instead of directories. The blacklist works by matching any filepath that starts with any of the entries which is why just ending / removes all the files in the directory and all subdirectories.