Xylem is a water-conducting tissue in plants. It transports water from the roots to the different parts of the plant. If the xylem of the plant is removed, upward movement of water will stop leading to wilting of leaves and ultimately causes the death of a plant.
Xylem transports water and minerals in plants from roots up to the stem, to the leaves. If Xylem is removed from a plant, the plant will not be able to transport water to leaves, hindering various processes like photosynthesis, transpiration, growth etc. The plant will initially wilt and then ultimately die.