Don't know what your Lever clamps look like, but anytime we try to remove anything seized we spray PB Blaster on it a few times and wait at least one day,
Wow 2014 and the lever clamps are already seized, are you supposed to lube them yearly?
Should you break the lever clamps before cutting the cowling, then replace the lever clamps?
A new cowling is going to cost a lot of money, keep that in mind before you lose your patience.