When you use the built-in functions for manipulating roles and permissions, the cache is automatically reset for you, and relations are automatically reloaded for the current model record.
See the Advanced-Usage/Cache section of these docs for detailed specifics.
If you need to manually reset the cache for this package, you may use the following artisan command:
php artisan permission:cache-reset
Again, it is more efficient to use the API provided by this package, instead of manually clearing the cache.