Unfortunately you were lied to, pre-made water does not have anything to do with your nitrogen cycle. There has to be bacteria to eliminate ammonia in your tank. There are many ways to cycle a tank without fish. Right now you need to take back your livestock and start fresh. Is that a 35 gallon hexagon tank? Did your LFS know what your setup was? They should never have sold you the fish you have, they will not survive, let alone thrive in your tank. Anemones do not do well in those tanks, the tanks are deep and hard to get sufficient light too given the limited sizes you can use. I just got rid of my 35 gallon hexagon, so I know them well. It is not a good set up for saltwater. That is your problem, now for the solution.
Get rid of you livestock, all of it. Fish dying means it is not safe right now. You need about 30lbs of liverock (cured). This will cycle your tank, just test your water daily until the nitrite and ammonia are zero. It could take a week, or a few weeks. You will never know for sure how long, it varies from tank to tank. Then you can figure out what kind of livestock. Clowns, Basslets, a few others you can chose from and keep safely. Let us know what kind of lighting you have and what kind of filtration you are using. Water parameters would be good too. Then you can start figuring out where to go from there.
Research is key here, make sure you really study what all is involved with properly caring for a tank. Study the livestock you want, make sure this is something you are really prepared to do. It is not always an easy hobby. To properly maintain a tank takes patience, and a lot of it. It is very rewarding though, and an ounce of prevention is worth a pound of cure. All the cliches are true in the hobby, that is another thing to heed. I am by no means an expert, I have been doing this 1.5 years but I will help you any way I can.