The sync password never leaves this device. It is what encrypts the copy kept in the repository, so it must be the same on every device that shares it; the token only opens the repository. It is not the password that opens a vault created on this phone - that one is asked for on the home screen.

To remove the code, type the current one above first. The code seals the copy kept on this device. It can be digits or a full password - a longer one is harder to guess, and it is asked for only when the vault opens. Removing it leaves the vault readable by anyone holding the phone unlocked.