Hello Cnoa27,

You should be able to change the raid level as you have enough space.  Now if the option is greyed out then that means that the MD is doing something in the background with the virtual disk. Normally if you wait a little bit & let it finish the task that it is doing the option will become available. You should be able to right click on the virtual disk & see an option to change the raid level.  

Please let us know if you have any other questions.

You may want to check the diskgroup instead of the virtual disk to see if that will let you change the raid level.

In the interest of your data, I wouldn't recommend raid 5 setups with more than 6 or 7 drives, especially if you're using 1TB (7200rpm) or larger drives as the risk of dataloss becomes much larger in the long run.