You can probably unhook the batteries for a little while and that should clear up the code (although it will stay in the computer as inactive).
But if you keep getting overboost codes with the EZ, I'd check to make sure you have a good connection at your MAP sensor. The EZ should be clipping the voltage to prevent the computer from seeing the higher than normal boost. If you have a solid connection, you may want to get in touch with Edge as the boost module portion of the EZ may not be working correctly.
Justin