Before taking this mission, head to the roof of the mansion and take the Maverick, then land it outside the mansion at the bottom of the stairs. Head in and start the mission:
You killed Diaz and now people are refusing to pay protection money! Tommy brags he can change that in 5 minutes and you need to fulfill his claims. Enter the Maverick you parked before and fly to the North Point Mall. Enter the mall and use a Uzi or M4 to destroy all the shops' windows, It does not matter, in which sequence you do them, just be fast about it. Cops will appear shortly after you shot the first ones and you will gain a five-star wanted level.
Just run from them and continue, do not bother killing them if not necessary. Once you destroyed all of them, the mission is complete and the wanted level will vanish.
Rewards: $2,000; you can now buy assets.