The grid list which appears in the dropdown control on the login page can be personalised from the "Grids.txt" file located in the Data Dir folder.
If you double click on Grids.txt it open up in notepad as below:
3rd Rock Grid,http://grid.3rdrockgrid.com:8002
Avatar Hangout,http://login.avatarhangout.com:8002
Cyberlandia,http://hypergrid.cyberlandia.net:8002
Francogrid,http://grid.francogrid.net:8002
Legend City Online,http://login.legendcityonline.com
Meta7,https://login.meta7.com
OSGrid,http://osgrid.org:8002
ReactionGrid,http://reactiongrid.com:8008
The Gor Grid,http://thegorgrid.com:8002
The New World Grid,http://grid.newworldgrid.com:8002
WorldSimTerra,http://wsterra.com:8002/
Your Alternative Life,http://grid.youralternativelife.com
The format is: [Name of the grid], [Grid login URI] (Notice that the name and the URI are seperated with a comma (,)
Simply delete the lines you don't want and/or add the ones you do need in the format explained above.