You can delete an application history on your iPhone by clearing the storage space or deleting history on any app. To clear up storage space, you can go to Settings > General > Storage or iCloud Usage > Manage Storage. Then, find the app that takes most of your space and remove it from your device. To delete history on any of your apps, you can also move to Settings, select the app (e.g Safari), and select 'Clear History and Data.' Repeat the same step to delete more history on other apps.