I’ve heard you can start removing push-pull pairs on each side (normally 3 push-pull pairs per side), but as noted this will be suboptimal. You’ll have to re-bias if you do this. You can also just drop the tube biases down from the standard 40mA to say 35mA, for a slight reduction in heat. Rogue is great to chat with if you want their guidance on this.
If you’re concerned about heat dissipation, an amp with a dozen KT88 and 6 small tubes is not a great match. As others have suggested, it’s probably a good idea to trade the amp in. Many audiophiles without heat concerns would love to have that amp!