Jerk paste is really easy to make.
It's scallions, allspice, thyme, garlic, habernaro or scotch bonnet pepper, black pepper, a bit of cinnamon and nutmeg, some lime juice, salt and a little oil.
Some people add onion, shallot, ginger, sugar, soy sauce and other stuff.
But the basic way to reduce the heat is to cut back on the hot pepper. Make it with one or even 1/2 of one. But it won't tatse the same without it. Remove the seeds and ribs to lessen heat.
There are bazillions of recipes through google. I think the best are on Pepperfool.com.
Peruse them and pick one and cut down on the Hab or Scotch Bonnet quantity.