It is highly likely that the trusses are an integral part of the roof construction and on no account should you remove them.
Trussed rafters began to be used in the mid 1960s and used pre-fabricated frames fixed in a 'w' shape. The timbers are fixed to each other using metal plates.
Although the trusses look fairly insubstantial on their own removing them will seriously weaken the whole structure of the roof.
If you have already removed any trusses I would strongly recommend that you seek advice from a structural engineer or surveyor to ensure that no supporting timbers have been taken away.
