I wouldn't disable the alarm. If you're getting up in the mid to high 70's, that's when you need to be notified. You don't want it getting any higher, so you need to stop it there. High temps can shorten hardware life and decrease performance.
If it's just a temporary solution, remove the side of the case, and point a box fan at it. Buy a tube of thermal grease, and reapply on the CPU. Make sure the CPU fan is on tight. This should (hopefully) bring your temps down to mid 30's - mid 50's.