TDAS D5-300 - Question for single hd

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Hello everyone..
I have a D5-300 with the first four slots in raid 5.
Now I would like to add an additional hd in the fifth slot, I know that it is not possible to increase the raid
without deleting it and redoing it, but I would like the fifth hd to be a single hd....is it possible to do it?
If so, how? The RAID manager sees it, but does not give me the possibility to initialize it....
Thank you very much.....