That looks like a caulerpa, which is a great nutrient consumer. I'd leave it in to compete with that hair algae. Once excess nutrients are consumed, it will die out on its own.
All that algae growth is Mother Nature's way of helping to balance your ecosystem. If you want no plant life in your tank, you have to starve them of nutrients.
If you don't expect to lower nutrient levels, you will always have plants of some kind. If so, choose the plants you WANT, like decorative macros, an algae scrubber, or a chaeto fuge.