Need to remove shared storage from EV cluster configuration

Dears,

We have a 2+1 EV cluster setup with windows cluster running windows 2008 R2 EV version 10.0.3. We had provisioned extra storage for the vault store which we want to reuse. There are two instances setup, one for mailbox archiving and another for journal archiving, each running on one node and one node is standby for any failover. There are two LUNs unused which we want to take out from cluster, one LUN per instance. Can we safely take it out. Are there any precautions we need to take? Any issues... Just to mention again these LUNs have not yet been used for stores.