You don't get them out. They are part of the system now. There are some bugs that are a little obnoxious in an indoor bin (fungus gnats, fruit flies) that you might want to control, but, in general, small bugs in the bin are a natural part of the composting process. They will eventually find their way in no matter what you do. The problem is when they find their way out.

You do not want them out. That is where you are. You want them in and to stay in. That is where they work. They are working to break down material for or along with the worms. When their job is done they will magically disappear. Without bugs and worms doing their jobs our world would be a very unpleasant place to be.

What did the worm bin parent leave to use as bedding? Usually more bedding solves all problems in a worm bin world.

Strangely people can become very attached to their worm bin the little world which makes good use of kitchen scraps that otherwise fill our world with garbage. No doubt they trust you very much or they would not have chosen you to care for their vermicompost system. Feel free to request some black gold or vermicastings for your gardening as payment for taking care of them. Possibly they might even share a cup o worms so you can start your own vermicomposting system to make good use of your own kitchen scraps.

Tell me you did not use Raid?!?

There are a few bugs like slugs and centipedes that you could kick out of there if you see them.

Here is a link that might be useful: Other bugs in the compost bin

Equinox has it right. Don't worry about the bugs in the bin, just put a thick layer (two inches or more) of shredded paper on top. That way they'll stay down below and any bugs outside won't have nice material to lay eggs in. When you add food or whatever, put it _under_ they layer of shredded paper.