This manual describes how to stop syncing of products via Google & Youtube channel in Shopify. This is needed if you are using Google Shopping Feed Pro for Shopify. If you are using multiple data sources with Content API, then the Content API source will interfere with the other data sources in Google Merchant. At least if they have the same feed labels.

On the left look for [1a] `Sales channel - Google and Youtube`. Click on it. Then click on the [1b] `Settings` tab.
On the left look for [1a] Sales channel - Google and Youtube. Click on it. Then click on the [1b] Settings tab.

Then scroll down until you find [2a] `Your product feed settings`. Then on click on [2b] `Manage` button for `Product sync settings`.
Then scroll down until you find [2a] Your product feed settings. Then on click on [2b] Manage button for Product sync settings.

Then choose [3a] `Manually add your products or sync them using a third-party app` and then [3b] `Save`.
Then choose [3a] Manually add your products or sync them using a third-party app and then [3b] Save.