Close all doors connecting the basement to the rest of your home and open all doors and windows that lead outdoors. Turn off all lights in the basement and stand or sit quietly, keeping an eye on the bat. Ideally, the bat will use this opportunity to simply fly out of the basement on its own. If it hasn’t yet left after 10 to 15 minutes, you will need to capture it.
Put on a pair of heavy gardening gloves and keep a container such as a box or coffee can nearby. Wait for the bat to land. Slowly approach the bat and place the container over it, then slide a piece of cardboard between the container and the wall or ceiling to hold the bat in.
Take the container outside and remove the cardboard to release the bat. Make sure that it has exited the container and flown away before you take the container back inside.