You can delete the target in grid control, edit the agent targets.xml (take a backup first) and then bounce the agent and rediscover it in grid. Please note this may not work, the agent has a habit of rewriting parts of the targets.xml when you bounce it. Also, when you discover the target again in grid manually, i believe you can call it what you like. Try it out on a test server first.

I suspect a similar set of steps for database control, but I don't use it so couldn't be sure.

Bazza