If you want to be cautious before deleting the application (good idea), you can export your current savegame (the savegame contains your crossbars, gear sets, macros etc.) via the PS4 settings menu to a USB stick (50MB, maybe 100MB, should be enough. Make sure the stick is FAT32 formatted, NTFS will not work). You do NOT need to backup the whole application (several GB).

After that, wipe the application, reinstall from the PSN store (WITHOUT Heavensward), restore your savegame (if necessary at all), log in again, take a break (about 6200 MB will be downloaded after logging in), and should be back in business.