You need to give it some deep thought and expand upon:
1. Is it safe to decommission the system. If not it needs to be made safe or the risks controlled - eg materials which may do you harm asbestos in the flue, asbestos in gaskets, chemicals in system, is it gas or oil fired, turn off gas??, turn off electricity, remove fuses, turn off oil ??, make sure valves are holding and that electricity is in fact isolated, allow to cool down, etc
2. Once it is made safe or risks are controlled, carry out correct procedures - drain system, disconnect pipework, cap off any ends, terminate electrics, if oil consider draining down oil, all to environmental protection acts, etc, remove components.
3. Once components are removed ensure they are stored safely and then disposed of safely and correctly.
You can write a lot of words about it - think about dangers and procedures.
And Clipper while you are at college work hard at it the industry needs good keen guys