acaman: Maybe in US, but not in EU. And CDPR is an EU company.
Fr0z1nDuDe: Oh really? There is an unspecified law in the EU that prohibits you, the police, and private security to remove unwanted individuals from your private property. That. Is. Fascinating.
Now you're simplifying excessively. Sure, the comment they made was not very specific, but too much simplification does not help much.
Generally, you are allowed to defend yourself across the EU, though the specifics depend on the criminal law in each country, and countries do have different criminal laws. There is, to my knowledge, no uniform rule of thumb or general principle that can be applied regarding self defense.
And there are very significant risks involved in the DYI foot-to-ass approach. If you remove someone from your property yourself, rather than having the police do it for you, then you are at risk of being charged with assault. It won't necessarily stick but some countries can indeed have ridiculous ideas about the police having a complete monopoly on use of force.
Suppose the person being removed is struggling against your removal of them? What do you do? The obvious thing is a few good kicks and a punch or two probably wouldn't hurt, but this might make you the aggressor in the situation. Does it sound ridiculous? It does to me as well. But it is what it is.
The point is, the specifics really depend on the criminal law in the specific country, and that can be rather restrictive of what you're allowed to do.