To remove the H2 JDBC-driver from your EAP6 simply remove the relevant part from your standalone.xml:
<driver name="h2" module="com.h2database.h2"> <xa-datasource-class>org.h2.jdbcx.JdbcDataSource</xa-datasource-class> </driver>
Or with cli:
/subsystem=datasources/jdbc-driver=h2:remove