Deleting files & folders on external (SD card) storage

I have a number of devices with different versions of Android ranging from Android 5 to Android 10. In addition to internal storage, all my devices also have external (SD card) storage. I have no problem creating files, reading,and writing them on my external storage, but none of the file managers I have installed so far will allow me to delete a file or folder. They all suggest I need to get permission for delete access to external but fail to tell me in an understandable way how to obtain this permission. I've even recently installed various apps with names like SD Card File Manager which explicitly claim they will delete files. However, when I select files or folders to manage the delete option is always greyed out.
In desperation I have had to remove the SD card, load it onto my computer just to delete files and folders.Surely there must be a straightforward way of doing this directly on my Android devices?

 

I have tried numerous file managers/explorers etc. Yes, they can all access my SD card and create / view / edit and copy folders, create / view / edit and copy files, all without any problem whatsoever. The only thing none of them will do is to delete a file or folder on the SD card as they keep telling me I don't have permission to delete. This is the same on ALL my Android devices (phones,tablets, different versions of Android from 5 to 10).

 

I have so many SD cards ranging from sizes of 4GB to 512GB that I can't recall how / where each card one was formatted. I suspect many were formatted on my Windows 10 computer, but, wherever it was formatted, I never have any problem reading / writing contents on Android, only deleting.

Because I frequently transfer large numbers of files from PC to Android I found that transferring files wirelessly from PC to Android is a nightmare.For example, yesterday as a test of latest technology, I tried copying about 128GB of files wirelessly from one Android 10 to a brand new Android 10 device which took about 7 hours. I've also tried connecting to Android via OTG cable and copying but, that can take hours too and lack of power supply risks my Android device totally running out of battery. So I intend to always continue taking SD card out of Android device, copying on PC before replacing card on Android device. Is this likely to be a reason for my deleting problem?

 

I attach a Properties statement taken a few minutes ago of one of my MicroSD cards (400GB in this instance). You will note it is FAT32 formatted. Folders and files on this card when mounted in an Android device can be read / written / copied and moved quite happily. But, as with all my SD cards, Android steadfastly refuses to allow me to delete anything. On this card, as always, while mounted on my PC I've just had to delete what I don't want before reinserting this to the Android device.