A) Remove Cluster Disk and its dependencies from SQL Server
1) Click on Role  > SQL Server Roles > Resources >then click on SQL Server  
2) Right Click on SQL Server (Other resources ) > Properties 
3) Right Click Sql server properties > then click on dependencies > select on Cluster disk 3 and then click on Delete Button  
4) Then Go to Storage > DISK > Cluster disk 3 > as of now already assigned to SQL Server refer to screenshot.
5) We have to remove Cluster disk 3 assigned from  SQL SERVER (MS SQL Server)  to available storage.
Click on Storage > DISK > Cluster disk 3 Right click > Remove from SQL SERVER (MS SQL Server)  > then Popup will open (Are you sure want to remove the select disk from SQL SERVER (MS SQL Server)   ) >click ok 
6) After removed from Cluster disk 3 assigned to from SQL SERVER (MS SQL Server) > now it will show available storage in Assigned to of Cluster disk 3 respectively.
Even in Role of SQL Server > Resources > Cluster Disk 3 is removed and same as  from Storage > disk >Cluster disk 3 is removed.
  
  
  