That is a ramshorn snail
Technically harmless.
However, they do reproduce very rapidly. Most people don't mind them until they have 100s. I'd say take it out just to prevent any future problems. (it's much easier to remove 1 than 100 later)
It would be absolutely fine to leave it in. You can take it out if you want though - the only time you would start killing some is if your tank became over run with them. They will eat algae so you might as well leave it in.