1. In the Littledata app, go to the Connections tab, then click Disconnect on the Facebook Ads connection:

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.