No; but you can delete the mdisk and recreate it with a different RAID setting.
The Storwize system will move any data to the other mdisks in the pool. Of course you need to have spare capacity in your pool to do this. Having different types of mdisks (with different RAID settings) in one storage pool is not recommended. See the Storwize documentation :
https://www.ibm.com/support/knowledgecenter/ST3FR7/com.ibm.storwize.v7000.630.doc/svc_mdiskgroupovr_1bchdu.html
And this article on DW:
https://www.ibm.com/developerworks/community/forums/html/topic?id=169dbc73-66de-4a80-8851-ed9c7911de92
It might be that the GUI won't allow different RAID types in one storage pool, in that case you must use the command line on your Storwize system. The GUI is trying to enforce best practices to avoid potential performance problems.
Kind regards, Groetje,
Marcel Anthonijsz