I'll try to give as much information as I can based on what you've told us, but we will need some more information.
Yes, you can move it on your own provided that you do it carefully and without damaging the foot of the anemone. It is easy to remove them from a smooth surface such as glass, especially if you use a credit card or something similar to loosen part of the foot. If it is in as poor of health as you describe, it likely will not be very firmly attached.
However, getting it to take hold on the rocks may be trickier if it is unhealthy. If it has climbed to the top of the glass it is likely not getting enough light, and will climb back up there if you move it. If this is the case it would be better to leave it where it is.
As for the rocks, since you have experience with freshwater I assume that you know you should never remove the gravel/substrate of a freshwater tank and clean it. This is where much of your biofilter/ beneficial bacteria live. The same is true of rock in saltwater tanks. You should never remove and clean or dry it out unless you are completely taking down the tank and wish to store the rock dry. By doing this, you destroyed the stability and cycle of the tank. With much of the bacteria that support the animals dead the tank will now have to go through another (probably smaller, if you left the sand and filters alone) cycle. You will need to monitor ammonia, nitrite, and nitrate during this time and perform frequent water changes as needed to protect the inhabitants of the tank.
We do need to know the tank's parameters (particularly ammonia, nitrite, and nitrate as I mentioned above) and especially the lighting used on the tank. Since many anemones rely heavily upon photosynthesis,
the type and strength of your lighting is very important. If the anemone is turning white or pale, it is an indication that it is losing its zooxanthallae because your lighting is not strong enough to support it.
So, test the tank's parameters, find out and tell us what type of lighting the tank has, and if at all possible,
post a picture! This will help a lot in terms of identifying the species of the anemone and the specific problems that it seems to be having.
As for your other thread being closed, some people have a hard time telling someone who is genuinely very inexperienced from someone who is trolling (trying to post something inflammatory to get a response). I saw your other thread and did not think that to be the case, but then I have spent probably way too much time on the internet and usually find it easy to tell the difference.

Someone else thought you were trying to cause trouble and asked a mod to lock the thread. As long as you check back and respond to the people giving replies you shouldn't have a problem.