What's your question? Ask

How is the drainage in the container? Is the soil overly wet? The plants could have suffered from root rot of this is the case. On the flip side, air pockets in the soil could prevent the roots from taking up water or nutrients, which could also lead to the demise of the plant. This article will help determine if the plant is alive or not: https://www.gardeningknowhow.com/plant-problems/environmental/how-to-tell-if-a-plant-is-dead-and-how-to-recover-an-almost-dead-plant.htm

You certainly can send an image, but you are correct in that it looks like an ornamental grass.
You can bend and scuff the lemon grass in your fingers and you should smell the citrus lemon smell. Even small plants should have the lemon essence.
I do find my plants slow growing to start and then will take off.

https://www.gardeningknowhow.com/edible/herbs/lemongrass/learn-about-growing-lemon-grass-plant.htm

The most likely cause of the wilt is under-watering - how have you been watering it? Is the soil dry to the touch? Lemongrass should be watered regularly. The soil should be kept evenly moist but not damp/soggy.

For more information on growing lemongrass, please visit the following link:

https://www.gardeningknowhow.com/edible/herbs/lemongrass/learn-about-growing-lemon-grass-plant.htm

The younger plants are much easier to remove; however, it may also help to thoroughly wet down the area for about 15 min. or so. This will usually make the ground softer and pulling/digging of plants easier.

Yes pull out the roots of the dead lemon grass so that the new shoots have root space. You can also prune off dead ones leaving the dead roots in to decompose, not the best approach however.

You simply use a garden fork or sharp shovel and lift up the plants. They can be split by sometimes breaking them apart with you hands or sometimes you may need to cut through the root system with a clean sharp knife. The smaller plants can then be potted up to winter over.
Here is a link with more information.

https://www.gardeningknowhow.com/edible/herbs/lemongrass/lemongrass-winter-care.htm