This is not a vocabulary problem, that was the closest selection. - there is no suitable selection for this issue.
My setup. Fedora 16, ubuntu Oneiric CentOS server. Mysql database.
Fresh install to learn og from Brian Lewis's tutorial. Drupal 7.12, all modules are latest updates. og-7.x-2.1.

Set up a few trial groups while learning.
Have since developed a usable list of groups in Groups Audience from which to choose but cannot find a way to get rid of the trial group names.

--I have refreshed and used different browsers, cleared the cache 7 times, Switched Group Audience off and on.
--I have deleted them from Content, deleted the Content Types and reconstructed them but the list remains.
--I can add new groups to the Group Audience and change the names, these display as entered but I cannot remove any.
--Only the Organic Groups module is turned on, og-ui, og register, og views integration, og access control were on and used to add fields but are now off -- All remain active when adding content and the fields are remain visible and useable in .
- og does not display in < Configuration> with those modules switched off.

og modules are off and module removed but still visible in content types linked to og, this is puzzling!

The only way I have found to get rid of rows is to delete the database and reinstall -- not an option on the site now under construction.

Table og.
Use phpmyadmin to alter field contents. The altered contents remains in Groups audience.

My Groups >> Groups audience data [table og].
use data7;
select * from og;
displays the data which can only be altered not removed.
+-----+------+-------------+----------------------+-------+-----------|
| gid | etid | entity_type | label | state | created

+-----+------+-------------+-----------------------+-------+-----------------|
| 6 | 10 | node | This is event #1 | 1 | 1335931712

Content of this name was deleted from database.

field does not dislpay in aplhanumeric order and cannot be altered, it seems fixed to gid order which makes searching a list of groups difficult.