If you want to remove a custom field, you can delete it from within your custom field settings.
📎NOTE: This will remove the custom field from all employee profiles it's assigned to. If you're only wanting to remove it from some employee profiles, you should unassign the field from those employees.
Click your name in the top-right corner, then click Settings.
On the settings menu, click Employee data.
Click Custom fields.
Next to the relevant custom field, click the trash can icon.
Click OK to confirm you want to delete the custom field.
The custom field now no longer shows in your settings and is removed from all employee profiles to which it was assigned.