Prior to version 9, Sitecore use MongoDb to store analytics data. If you don’t need analytics features and don’t want to maintain MongoDb, you may like to configure Sitecore as CMS-only mode. Based on Sitecore document, it is pretty straightforward.
In Sitecore configuration file “Sitecore.Xdb.config”
<setting name="Xdb.Enabled" value="false" />
It prevents the data from being saved to the database. Now it is safe to remove MongoDb connection strings.
But the tracking is still happening. there is a Sitecore ‘Submit Queue’ that flushes captured data to the server disk (the ‘Data\Submit Queue’ folder by default). It expects MongoDb comes back online, a job process submits the data to MongoDb from the disk “Submit Queue” folder.
But this may cause performance issue to authoring server and even possible item publish error when server runs for a period. To solve this,
In file “Sitecore.Xdb.config”
<setting name="Xdb.Tracking.Enabled" value="false" />
In file “Sitecore.Analytics.Tracking.config”.
<setting name="Analytics.UseSubmitQueue" value="false" />