Does deleting a user delete their content?

When I am in the ‘manage users’ section of the webpanel, I see a disk usage amount for each user. If I delete a user, will it delete all of the content that they placed on my domain or will all of their content stay? Will their disk usage be deleted, and if so, how can I delete the user without deleting their uploaded content?

Well, try resetting their users FTP or shell password and not informing them about it. This way they cannot access the web space