No, you would need imperative for that. Άλλαξε το παντελόνι σου (for one-time actions; for example "change your trousers now") or Άλλαζε το παντελόνι σου (for habitual action; for example "always change your trousers after work")
Interesting. Now I realise imperatives have not been covered yet. So would you say both forms of imperative are like present continuous vs. simple present in English?