Step 1: On the Navigation Pane, under STORAGE, select Block.
Step 2: On the next page, select the Consistency Groups tab.
Step 3: Next, select the CG and click the pencil icon to open the Properties window of the CG.
Step 4: Open the LUNs tab in the CG properties window, and select the LUN or LUNs to be removed from the CG. Click the More Actions dropdown, and select Remove from Group.
The LUN should be successfully removed.