1. In the Littledata app, go to the Connections tab, then click View Details on the Facebook Ads connection, then Disconnect:
You will now stop receiving daily cost data imports to your Google Analytics account.
2. (optional) Delete the import files from your Google Analytics account. Go to Google Analytics Admin > Data Import > click on FACEBOOK LITTLEDATA IMPORT > select the files you wish to delete and hit Delete Selected:
You have successfully disconnected the Littledata Facebook Ads Cost connection.