Am I sinful for practising outdoor Da‘wah activities without my father's permission?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

It is permissible for you to go out for Da'wah (i.e. propagating Islam) without your father's permission, unless this leads to violation of his rights upon you or your obligations towards him.

Allaah Knows best.