English Translation
Please leave.
Just as a note “proszę wyjść” would be the more formal/polite form I believe.
Well, it’s not the most polite form, but it’s more polite than Wyjdź!. Czy mógłby Pan/Pani … would be the most polite form. The translation matches the tone of the sentence.
The Polish sentence contains a punctuation error – a comma is necessary. Proszę, wyjdź. is correct.