You'll need:
A heat gun or torch rather than a hair dryer (hair dryers are amazingly low heat...product liability laws are such that they really don't make them hot enough to badly burn yourself, which isn't hot enough to loosen locking compound) a 2.5" or wider nylon strap wrench, and an upper receiver vise block (the clam shell type, not the one that uses pins to hold the upper to a block).
The jam nut backs away from the handguard (towards the receiver). With the gas system removed, the handguard unthreads from the barrel nut towards the front, and then off. Then unthread the jam nut from the barrel nut. The barrel nut can then be removed from the receiver with an appropriate wrench head or armory tool.
The only place there should be any locking compound is under the jam nut. The barrel nut is greased, not locked in any way.
Steve/RRA.