Best way to repaint nearly new trim

We're planning to replace all the trim in our house over the next couple of years (to something with more impact). In the meantime, the "golden oak" trim is really bothering me, and I'd like to paint it white, or stain it darker.

Can I strip it with a liquid or gel, or do I have to sand the finish off before priming and painting (or staining)?

Any other tips or tricks to make it a bit easier?