Clearing out all the old data and having a fresh start can be a good thing, especially if errors start.
Keep in mind when this is done, all the Add-ons, Sources, and any Build will be gone and need added back in.
Uninstalling and reinstalling Kodi is the best method to get rid of all the old data and start fresh.
There are also utilities that can delete old user data and have Kodi boot clean.
Doing a Fresh Start is also needed when a new Build is installed as old data can mess up a Build from installing correctly.
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Read Here for the best current add-ons and how to install them.