If I have a bench warrant for a DWI because my lawyer missed the court date, how do I get rid of the bench warrant?

Typically a warrant is only put in place if the defendant misses the court date, not the lawyer.  That being said, if you missed the court date, you should go to the court immediately, check in with the clerk's office and explain that you want to clear a warrant.  They will then have you check in with probation, and send you in front of the judge.  The judge will remove the warrant and probably impose a warrant removal fee.  You may want to contact your attorney to come in with you, in the event that the judge decides to set a bail, since a court date was already missed.