If for some reason you don't plan to use CRM sync anymore, you could disconnect your CRM in a few simple steps.
Disconnect CRM
Go to the Settings page from the main menu.
Navigate to the Integrations tab.
Click on the Three Dots button against the connected CRM
Select the Disconnect option in the opened menu
Confirm the action in the opened confirmation popup
Once the CRM is disconnected you won't be able to sync data from and to the CRM.