I did this a couple months ago. If you want the fish keep them.
What you gotta do is get a bucket or a cooler and put your live rock in it and put wet paper towels over them. Next get another bucket for the fish and corals. Since you have no corals this bucket will just be fish. Airate the water.
Once everything is out shut down all pumps and filters and remove the hood.
Get the biggest net you have and start scoopen. Just throw the cc into another bucket. Once you get it out you can do two things. one put the lr in and surround the bottom with sand. or two add the sand then aquascape.
To make up for the loss of water add premixed salt water to the tank and turn the filters pumps on and relocate the hood. Once it clears up add the fish.
Forgot one step after there is nothing but water in the tank no lr fish or cc let it settle. than siphone the debris off the bottom of the tank. You may have to do this more than once. the follow the rest I told you. Hope this helps.
Adam