Demolition is a very dangerous occupation if you are unsure of what you are doing exactly, so this is why all staff working on a demolition site should be fully trained. There are specific courses that can be taken to gain access to the industry and also many different forms of demolition, below explains some of these various factors involved with demolition work;
Becoming a Demolition Worker
How to become a demolition worker - Demolition work is closely related to the construction field so many wanting to access the industry from an age under 18 would have to either become an apprentice in construction. 
Alternatively they could wait until they are 18 years old and there fore old enough to take the demolition courses but the knowledge of construction would be very useful for those wanting to enter demolition.
Skills Needed by Demolition Workers - There are certain skills you would require to be a successful demolition worker as well as the qualifications including; good manual skills for handling tools etc, responsible way of thinking regarding working regulations, the ability to work well as part of a team and feeling comfortable whilst working at height.
The qualification most people work towards to become a demolition contractor is the NVQ in Demolition Levels 2 and 3. Once trained there are other courses available that will further your knowledge in the area.
Different kinds of Demolition work
Types of demolition - There are various types of demolition for different materials for example they would use a different method of demolition for bricks than they would for timber. The three main types of demolition include explosives, by hand or using heavy duty plant machinery and it depends on the size and stability of the structure as to what method is used.
There are lots of different types of structure that have to be demolished by professionals to ensure it is done correctly and safely. Some of the types of structure that would have to be demolished by professionals include the likes of; large bridges, residential buildings, factories of all kinds and wooden built structures such as barns. In some cases you would also require permission from your local governing body before carrying the work out. Also be sure the company you hire are a registered company so you know their work will be guaranteed and their staff fully trained.