I am not sure this is the simplest way, but you can change all the
genesis.json files (there are 3 of them if you used https://developer.algorand.org/tutorials/create-private-network:
~/net1/Node/genesis.json) to specify different addresses for the fee sink and reward pool.
If the reward pool is empty at the end of a reward period (or at round 0), there will be no participation reward distributed at the next reward period.
Concretely, if the reward pool is empty at round 500,000, there will be no reward for the period 500,000-1,000,000. If you fund the reward pool during this time, participation rewards will be distributed in the next reward period 1,000,000-1,500,000.