Chinese Phrase - I'm leaving
wǒ zǒu le
Literal: I Go [Grammar particle]
It may seem a little rude to westerners, but many Chinese simply say "I'm leaving" as they leave.. and leave it at that.
Check out this group of Chinese phrases too. You might find more useful Mandarin phrases. The current Chinese phrase "I'm leaving" appears in this groupCourtesy - Farewells