Facist Graffiti will most likly be there whether you like it or not, it's what you make of it that matters. Seriously take up the ideas of modefying the symbol to either have it being thrown in the waste bin or just the simple Swastika version of the No Smoking Sign which can even go on to promote the Dead Kennedys with Nazi Punks Fuck Off.
If your not one for graffiting, perhaps call the council and go through their government to get it sorted but I personally would not take that option, mainly cause I hate dealing with the government but it will more then likly take a long time for the to get around to.
Or clean it off yourself, maybe even offer to paint the wall or suggest the owner does, sometimes its best to get the owners permission first and show up with designs, specially for store owners, you never know they might just want to have a symbolism of WWI and the crushing of Nazi Germany on their wall as a show of loyalty, but then you can also say your being historically correct and have Soviet Russia reaching Berlin first like they did, therefore you're bring across communism with permission, just different fraising which I'm sure you can make up for yourself.
"Its one third social, one third educational and one third political" Yarra Socialist Party Councilor Stephen Jolly.