Bro I dont own YBZ but generally speaking, rust is common problem in fuel tanks, and specially due to poor fuel quality and humid weather conditions, over time rust develops in fuel tanks, so no need to worry much, just keep checking your fuel filter as a routine maintenance.
Sill if you are concerned try using a fuel system cleaner, cost around 1500 to 2000. You can find a fuel system cleaner from motorcycle decoration shops. I cannot recommend any brand bcz I haven't personally used until now.