If you decide that you want or need to capture a bat, you might be able to physically capture the bat, and release it outside.
Remember, bats should not be handled or touched with bare hands, always wear gloves. Bats have extremely sharp teeth. Although only perhaps one-half of one percent of bats have rabies, anyone who thinks they may have been bitten by a bat should immediately seek medical attention.
To actually capture a bat, you might try this technique:
Wait until the bat lands on the ceiling, or the wall, or in the corner, where you might be able to gain access to it. This will be much easier and more effective than trying to catch the bat in a net, or throw a towel or sheet over the bat.
Cover the bat with a small open container, like a box. While holding the box over the bat, gently slip a single, thin, flat sheet of cardboard between the wall and the box, trapping the bat inside the box, and, at the same time, creating something of a “lid” to the box when you move the box from the wall.
Keep the temporary box “lid” securely covering the top of the box as you bring the box down from the wall, preventing the bat from escaping.
The best time to release the bat is after nightfall. At that time, take the box and your bat outside to prepare to release it. Most bats cannot begin flying directly from the ground. You might have to hold the box above the ground, perhaps head-height, before releasing your bat. Gently tip the box sideways, and remove the lid to the box, allowing the bat to fly from the box, which it will likely do.
Alternatively, you might prefer to hold the box against high, rough wall, or trunk of a tree, and slowly remove the cardboard cover. The bat will likely cling to the surface of the wall or tree, rather than staying in the box.
At this time, you can remove the box, and allow the bat to cling to the tree until it is ready to fly away.
Click Here for instructions to capture a bat by Bat Conservation International: