Hello, I meet an embarrassing problem using Mod Organizer. I want to remove one mod that I no longer need but Windows denies me the access while I use administrator compatibility. I cannot either delete manually this folder located in D/Games/Steam/.../FNV/MO/Mods/
If anyone has a sufficient experience with MO, I would be happy to have an opinion. Thanks.

I doubt it has something to do with MO. I think it's the usual: you want to delete a folder inside the steam-folder or the steam-folder itself (after deinstallation) and get told you lack the user-rights.
It's so annoying.

Some things that might help: a) right-click the folder you want to delete, go to properties and under security you can give yourself full access, a reboot helps; b) as a rule of thumb: you can only delete folders inside the steam-folder or that folder itself when and only when there is no other folder inside the folder you want to delete. You have to delete those folders from the inside out.

Yes, you're right. I discovered that it is only a Steam related problem. I found a solution though.
I succeeded to manually delete MO installed mods in removing the subfolders. You have to be patient but it does work!

I would suggest temporarily disabling anti virus and uninstalling. Sometimes I have trouble with installing and uninstalling mods with the NMM. just remember to turn it back on again.