No, syringoma and sebaceous hyperplasia cannot be completely removed! You can only flatten the lump and leave what is left in the dermis or you will just create a hole in the skin. Over time (a few years), it will slowly grow back.
The idea of flattening them is so that you can cover it better with make up and lose the 3D effect which is almost impossible to cover.
This issue cannot be removed completely with any treatment, not because of the treatment used but because the growth exist in the dermis. But the gold standard is still CO2 laser due to precision and less collateral damage.
You can flatten it in a few sessions but the skin colour is always going to be different as the areas with syringoma or sebaceous hyperplasia is white devoid of melanin unlike your normal skin tone. Hope that helps.
