It's hard to give much advice without knowing exactly where you're located. One thing you do need to consider is that most turtles, with the exception of snappers, eat aquatic vegetation......so if you want the pond cleared of weeds and such, you may not want to kill the turtles.

What kind of fish are actching from it now? If it's bluegill, you can take some, but it would also help if you could put in a few predators, like bass.
If it's bass that are really small, you probably should take a bunch out and then make sure you have some type of forage for them as well. You can buy ( around here anyway ) fathead minnows by the pound. A few pounds of forage would go a long way to helping your bass grow. Bluegill would be another option for forage.

GH