If you delete or uninstall FulGaz, all your ride history and video downloads on that device will also be deleted. This data can not be recovered.
Your ride data is only stored locally on the device you rode on. Ride history is designed as a backup in case you skip uploading after completion or if you need to re-upload it shortly after. Ride history is not synced between all devices you have FulGaz installed on and the full ride history data is not stored on the FulGaz servers.
The complete ".FIT" data file is sent to you in the post-ride email and FulGaz can be configured to automatically sync ride data to sites such as Strava.
Please only delete or uninstall FulGaz if absolutely necessary!
If you must delete FulGaz, make sure you have uploaded all your rides from your ride history or have a copy of the data in the post-ride email (or synced on Strava, etc).
A note for Apple TV users: If your Apple TV device runs low on space, the tvOS will automatically overwrite data it deems unnecessary in order to create space for new files. This may include some of your ride data and video files. This is unfortunately outside of our control. One tip to reduce the chances of this is to always keep at least 5GB of hard drive space free.