Open Facebook and go to your profile
Tap Friends or Followers
Open your Followers list
Find the follower you want to remove
Tap the three dots next to their name
Select Remove follower
Confirm the action if prompted
To prevent future followers, go to Settings and privacy
Open Settings
Go to Audience and visibility
Tap Followers and public content
Change Who can follow me to Friends or Friends of friends if available
Set past posts and profile visibility as needed