To remove your last name from Facebook, you need to go to your settings and then click on the "General" tab. Next, click the "Edit" button next to your name, and delete your last name from the "Last Name" field. Finally, click "Review Change" to confirm the update and remove your last name from your Facebook profile. It's important to note that Facebook has certain policies regarding name changes, so you may need to provide additional information or documentation to make this change.