Partitioning your drive will erase everything on it, so make sure you've saved important files elsewhere before proceeding. You can find this in the Utilities folder, located in your Applications folder. You'll find this listed in the left frame. This will open a new window. This will enable partitioning on your USB drive. Ensure that "OS X Extended (Journaled)" is selected from the "Format" menu. This will make changing the partition sizes easier, but the drive will only work with Mac computers. The new partition map will be applied, and the "Partition" button at the top of Disk Utility will become active. This will open a new partitioning window. You can add as many partitions as you would like. You can adjust each partition to be as big or small as you would like. neighboring partitions will be resized accordingly. You can give each partition a unique label, which can be useful for telling them apart. The drive will format, which will take a few moments. You'll be able to see and access all of your partitions while your USB drive is plugged in, just as if each one was an individual USB drive. Because the format is "OS X Extended (Journaled)," the drive will only work on OS X computers. Windows doesn't support multiple partitions on USB drives without special tools.

TL;DR in Indonesian:
Cadangkan berkas yang ada dalam kandar USB. Bukalah subfolder Utilities dalam folder Applications, lalu pilih Disk Utility. Pilih kandar USB di bagian kiri jendela Disk Utility. Klik tombol Erase. Untuk mengaktifkan kemampuan partisi, pilih opsi GUID Partition Map dari menu Scheme. Klik Erase. Klik tombol Partition di bagian atas jendela Disk Utility. Untuk membuat partisi baru, klik tombol "+". Tarik ujung grafik lingkaran untuk menyesuaikan ukuran partisi. Pilih salah satu partisi untuk memberi label pada partisi tersebut. Klik OK untuk menerapkan perubahan pada tabel partisi. Mulailah menggunakan partisi baru Anda.