Pause one platform: Sources, untick "Include in syncs".
Remove a key: Sources, Disconnect. The key is deleted from the spreadsheet; gifts already copied stay.
Delete a platform's gifts: Sources, More, "Delete ... gifts from this spreadsheet". Nothing changes in the platform.
Remove your license from this spreadsheet: License, Remove key.
Remove everything: delete the spreadsheet. Its script, keys and schedule go with it. Also revoke the keys in Zeffy, Givebutter or Donorbox if you no longer use them.
