To disconnect the Event Horizon Labs Inc. internal integration from QuickBooks Online, revoke its access from the Intuit account dashboard:
Intuit account → Settings → Connected apps → Event Horizon Labs integration → Disconnect.
Revoking access immediately invalidates the integration's OAuth tokens. Any stored tokens on EH Labs' infrastructure become inert and are cleared on next run.
You may reconnect at any time via the Connect / Reconnect page.