I have an Octavia 2, is it possible to reset the service indicator without having to visit main dealer.

What service schedule are you on?

You can reset it via dash buttons (its in your manual)

A dealer is not permtted to reset a service light without carrying out a service (unless a fault means it has come on incorrectly).

Does that do bad things for the warranty (if applicable)? Not to mention bad things for the engine.

The schedule is set for variable but i have the oil and filter changed twice a year (8000) miles, thanks again.

Well out of warranty now - oil changed more than recomended by skoda so shouldn't cause any damage. thanks for post.