Hola Robert

You can use the present subjunctive as a command when it is for a formal "usted, ustedes", e.g.:

Pida usted disculpas / Pidan disculpas

But for the informal tú (which is this case in the question you encountered) you need the imperative form:

¡Pide disculpas!

Here are some lessons about using the imperative/commands bearing in mind the different subject pronouns and if they are affirmative or negative:

Forming the imperative for usted/ustedes/nosotros/nosotras (affirmative and negative commands)

Forming the imperative of tú for most verbs (affirmative commands)

Forming the imperative of tú/ vosotros/vosotras (negative commands)

I hope these help.

Saludos cordiales

Inma