"total" is being used as a verb, an action word, and comes with the sense of 'total destruction'. So to 'total' someone is to wipe them out, destroy them, kill them.
"sucker" is a person who believes everything they are told and is therefore easy to deceive. However, here, the speaker may be just using it as a general derogatory term in the sense that this other person is 'a loser'.
In another context, such as a movie where where aliens attack earth, one person might say to another holding a gun, "total the sucker' (the alien) where 'sucker' is used as a term of contempt for this alien.