I'm in the same situation as Ole, I registered for a new address on March 1st, I'm supposed to do the 90day report at the end of this month, I've been trying to do it online since morning but the Captcha number keeps showing error.
It can be done, you can talk to your current employer to give you a letter to cancel your visa in advance, according to the immigration, you can cancel it 21 days in advance.... then you go to lampang and start the process there.
I just canceled mine in advance till May 5.
Always remember to cancel the visa before the work permit if you're in Bangkok or else.... You'll overstay. 😊😊😊