Assuming that you are replacing everything from the weatherhead on down on a standard residential service, you can always extract the meter once the power is cut off.
Shut off the branches and main in the panel.
Check that the meter has stopped spinning.
Using a ladder, rubber gloves, and a clamp-on ammeter, verify zero current in the service drop, at the weatherhead. You don't want to disconnect any appreciable current. in the next step...
Using insulated cable shears, gloves, face shield, etc., cut the conductors of the service drop (one at a time, obviously
), cutting the 2 hots first, then the neutral. I like to cut them right at the utility side of the splices, if there is enough conductor length available. Tape up the hot ends of the triplex until you are ready to reconnect the new service riser.
You can now go ahead and remove the old meter pan and service riser/weatherhead, and can hack the old meter socket apart (I've had to use a sawzall a few times if the corrosion was serious or the meter was seriously "stuck"
) If the meter is burned or cannot be salvaged by cleaning the lugs, contact the utility.
On an installation that is old and deteriorated, pulling the meter with the socket hot can be quite risky. The old plastic or ceramic meterbase could fall apart, and drop the hot (unfused!) phase conductors into each other or into the metal enclosure. Bang!