Removing bats can be a tricky process, especially since bats are occasionally protected during certain months of the year. However, no matter when you are doing it, bat removal can be a tedious process that may take weeks to fully be completed.
You will want to first identify what entrance they are using as their main entry point, it is crucial to not seal this until the bats are evicted completely. You can, however, seal all other entrances, which will prevent the roost from growing. You can install a one-way valve on the main access point. This valve will not harm the bats, but is merely a chute for them so that they can leave the roost but are not able to come back in. You should put a slick material - like plastic - at the end of the valve, which is what prevents the bats from being able to get a good enough grip to pull themselves back in. When they are not able to get back into their roosting area, they likely will move onto a new place to try and roost.
Excluding your home, or sealing up your home, is tricky when it comes to dealing with bats. They are able to fit into extremely small holes as it is, and if you have a barrel tile roof they are able to fit under each raised tile. So, it is important to seal all holes up that bats could potentially use to gain entry. Once all bats have been evicted from the attic, you will also be able to pull out the one way valve and seal that hole as well. Meaning that your home should now be completely bat proof.
Finally, you should be ready for the sanitation. While this is disgusting and definitely the “dirty work” of the entire process, it is also important to keep you from getting sick from any remaining bacteria in the area. You should use thick protective gloves and wear a face mask when dealing with guano. When you remove the guano, dispose of it immediately. After all guano has been removed, go over the entire area with a disinfectant that will break down the remaining bacteria. This process will also help eliminate any odor that may be left behind as well.