For some Android versions it's not possible to edit tags or delete arbitrary files on external storage, unless additional permission is given to Poweramp.
Poweramp will ask for such permission of first attempt to edit tags / delete file on the storage if the permission is required.
Please note: "Documents" or/and "Files" standard apps are used for the permission dialog and if these apps are disabled / uninstalled / frozen or if ROM doesn't have these apps or if the apps are otherwise broken Poweramp will never get the permission and tag edit / file deletion will fail.
Alternatively, "Files by Google" app can be installed from Play, it restores missing components.