Make sure you're in the User Panel (click on
User Panel, and then click on the domain with the folder in question if
you have multiple domains). Click on "Password Protected Directories".
If your folder is not listed, click on "Find a Directory to Password
Protect". You should be placed in the domain's public_html folder.
Navigate to the exact folder you want to delete a user from by clicking
on the folder names.
Once you find the folder you want to delete a user from, click Protect. Check the checkbox next to the user you want to delete, and push Delete to delete the user.