This is what I see under advanced settings, I don't see "expunge".
Settings
General
Labels
Inbox
Accounts and Import
Filters and Blocked Addresses
Forwarding and POP/IMAP
Add-ons
Chat and Meet
Advanced
Offline
Themes
Auto-advance
Show the next conversation instead of your inbox after you delete, archive or mute a conversation. You can select whether to advance to the next or previous conversation in the "General" Settings page.
Enable
Disable
Templates
Turn frequent messages into templates to save time. Templates can be created and inserted through the "More options" menu in the compose toolbar. You can also create automatic replies using templates and filters together.
Enable
Disable
Custom keyboard shortcuts
Enable the ability to customize your keyboard shortcuts via a new settings tab from which you can remap keys to various actions.
Enable
Disable
Right-side chat
Move the chat box to the right side of the inbox.
Enable
Disable
Unread message icon
See how many unread messages are in your inbox with a quick glance at the Gmail icon on the tab header.
Enable
Disable