You will need a pair of appropriate extractors (available cheap on Ebay).
If your radio has the standard DIN system ( with 4 holes) then if you are careful you can use two bent pieces of wire coathanger or 4 small screwdrivers or Allen keys. It is a fiddly job so an assistant will be useful .If you insert into all 4 holes at the same time to unlatch the 4 retaining catches, then get your assistant to pull the radio out at the same time. If these 4 holes appear to be blocked , then they might be thief protected with small socket screws. These can be extracted individually using the appropriate size Allen key...As I said, overall it is a fiddly job.
RegWorts, June 2008