There are many reasons for deforestation. Some of them are -
Due to the increasing population there is more demand for building houses,schools,roads,etc.Due to this people are cutting down the forests in large number for the construction of housing and settlements.
Another is agricultural activities. Due to the overgrowing demand for food by the high population huge amount of trees are cut to grow crops.
Due to the pollution of land.The pollution of land is making it unfit for the growth of trees and most trees are dying due to not getting enough nutrients from the soil.This is also a reason for deforestation.
Due to industries. The industries like paper, matchsticks etc. need wood for manufacturing their products.Wood is also used as fuel.For this the trees are chopped down.