It doesn't seem to have screws nor a button. I need to rewire the cables because of them started to split. Any ideas how to get it out?
That's not a terminal block. That's a factory built connector, where the 2 small wires have been crimped onto the contact blade, then inserted into the connector void where it "snaps in".
Sometimes with a jeweler's screwdriver you can reach in and release the tang that holds the contact blade in the connector, but you're just as likely to break it. You will not be able to release those wires.
If this were North America, I would say, worst case, replace that connector with a ballast disconnect socket, which are readily available.