How to delete exported audio from Android (Nexus 5 / Lollipop) ?

Hello,

I'm using iRealPro v 6.1 on Android 5.0.1 on Nexus 5.

When exporting an audio rendition of a tune, the .wav or .m4a file is saved to an iRealPro folder on my Device SD card.
But without any special file manager application, it's not possible to delete these files in order to save space on th SD card.
I can see these files using native Android menu ("Storage" menu, then "Audio", then "from SD Card"), but they are greyed and I cannot make any actions on these files with android basic file manager application.

I think Android considers this iRealPro folder is the property of iRealPro application, and only iRealPro applicatiton is allowed to delete these files. Maybe special file manager applications I could Install could allow me to delete these files, but I'd rather use iRealPro to delete these files to avoid installing another app.

Is there a way to delete these files I didn't guess ?

There is no file deletion function for this purpose within iReal Pro.
Use a file manager app. Many use Astro.