Hi
you can destroy it by using inspect elements in browsers or fire bug ( specially in Mozilla) by following this instruction
in dboor just before second ok in attacking right click on target and select inspect elements ( or fire bug inspect elements) and change the value of target to 40 ( for WW) and other buildings IDs ( you can find the IDs in manual by clicking on building ( you will find some link like this
You must be registered to see links
[main building] that means main building ID is 15 ))
and then just click on secind ok