Well, your groups table definitely looks ok, so there is nothing wrong with that portion of it.
How about this one:
SELECT Bo_Keyword,Bo_Read_Perm,Bo_Write_Perm FROM w3t_Boards;
As for deleting all data from the tables, I'm not aware of a one shot command to do all at once. You would need to one table at a time (But you wouldn't want to do the w3t_Groups table because that one needs some prepopulated data).
There are 2 ways to do this, one is to download a database manager like mysqlman or phpmyadmin. This would allow you to have an online editor for your database and clear out the necessary tables.
The other way would be to do it by hand. Get a list of your tables by doing this:
SHOW TABLES;
And then one by one, exclude the w3t_Groups table, you would do this:
DELETE FROM tablename;
