The guild leadership periodically purges the guild of inactive members, removing them from the guild in-game as well as from the website. This is done so that the guild consists primarily of active players, and so that everyone knows who those players are. We also have a member cap limit in place, and deleting inactive members allows us to bring in new members without hitting that cap.
If you've become inactive in LOTRO, were removed from the guild, and want to say good-bye, please do so here in the public forum.
If you were removed by mistake (maybe you took an extra long vacation from the game but are now active again), we apologize for the error. Just send mail via guildportal to Calafalas (link on front page), and I will work with you to get you re-instated.