Jopik,
I'll just start by saying you should see if you can at least cut your loses and bring it to a good LFS that can take care of it and find it a good home.
Really good local fish stores will actually give you credit for a fine creaqture like this towards the purchase of something else. It won't be full credit of what you paid, but it's something.
I'm sure I speak for everyone on the forum when I say we'd rather you didn't just take it out and dispose of it. Thats the same as killing a dog/cat because you can't take care of it. there are shelters and this animals shelter is a better suited tank. Anemones are one of the hardest things to care for in this hobby.
The other part of it is if the anemone is left in the tank and does die it will foul the water in the tank and may kill everything else.
Just take it to the pet store and see if they will give you anything for it, if not just give it to them. If they can nurse it back to health they can make a dime and you can know you did the right thing.
When I say LFS I don't mean ***** or petsmart. while these vendor do sell anemones they don't have the proper lighting in thier tanks either. They are banking that the anemone will come in and be sold within a week or less before it dies in thier tank. That's one main reason why most of us don't buy from them.
You're right, you can do with this and everyone elses advice what you please, but if you ask advice and then don't follow it and animals die needlesly because you din't listen or didn't do research then not too many are going to find the time to help you in the future.
I started off in this hobby as a total Newb, I didn't knoww hat a cycle was, I didn't do much of any research except that I knew kind of what I wanted and what equipment I might like.
I bought a tank that had a huge lionfish in it and a bunch of nice live rock and live sand. Witht he help of this board and ALOT of reading I was able to pull the lion through a couple bouts of my stupididty (mainly a mini cycle from stirring up the sand when we moved the tank)
and a little over a year later, I've learned so much and can actually offer a bit of advise of my own from my experiences. I have a very healthy nice looking 120g reef now.
Could be the same story for you.......