I find this HSE page useful
Notifiable non-licensed work
Extracts of interest being:-
"It is the responsibility of the person in charge of the job to assess the ACM to be worked on and decide if the work is Notifiable Non-Licensed Work or non-licensed work."
"Notifiable Non Licensed Work will not normally include the following, which will continue to be categorised as non-licensed work (which is not notifiable), (assuming in all cases exposure is sporadic and of low intensity and will not exceed the control limit):
.........
..... removal, for example, of gaskets or asbestos rope cords from heating appliances, which can be left in situ for disposal or can be lifted out virtually intact, without substantial breakage;
and
....work to enclose or seal asbestos materials that are in good condition (and that do not require a licence);
I would ensure I was fully aware of the consequences of handling different types of asbestos containing materials and decide the level of disturbance to the asbestos you are going to cause in this particular job. My gut feeling would be the removal of a single DB would be Non notifiable and could be undertaken by non licensed contractors. But it would still need to be someone who fully understands the implications and of course would reference recommended HSE working practices to complete the work.
The resulting waste flashguard components will be classed as Hazardous waste which in itself has complications with transportation and disposal.The person taking them out will be classed as the waste producer. Using the Environment Agency document WM2 as reference you will see it is the waste producers responsibility to decide if a waste is Hazardous waste. Basically it is Hazardous Waste if it (any part of the waste) has something in it that looks (using naked eye) like it is asbestos or is understood to contain more than 0.1% asbestos. Small amounts of Asbestos Hazardous Waste is relatively expensive to get taken away properly. One flash guard might cost the same as a cubic metre of roofing material to get rid of.
In summary you need inform yourself adequately to be able to make the necessary judgments and decisions with asbestos, otherwise get someone else to deal with it.