Removing the transponder etc will do nothing, the code is in the ECU iirc. Need to take it to some place with a TECH2 computer (i.e vauxhall) and have it re-programmed. Easier and cheaper to get a 2nd hand ECU with transponder and chip, theres a lot of them kicking about because of people doing XE conversions.
Yeah disconnecting the transponder wont kill the ECU, the ECU needs to see the code from the transponder chip to let the engine run. what engine is it? your probly gonna need a new ECU, transponder chip and pickup to be honest, vauxhall will have your pants down