You might want to have a look at the SRM API guide.
In there you will find the UnprotectVms method.
You can reach this method by listing the protection groups with
$DefaultSrmServers.extensiondata.Protection.ListProtectionGroups()
Find the correct protection group (use the GetInfo method on a group), and on that group call the UnprotectVms method with the VMs you want to unprotect.
Blog: lucd.info Twitter: @LucD22 Co-author PowerCLI Reference
Thank You Lucd,
We dont have SRM in our environment we have EMC Recoverpoint for VM appliance which is somewhat similar to SRM.
Oops, thought you were referring to SRM.
EMC RecoverPoint does seem to have a REST API, but I'm afraid I have no experience with it at all.
You might want to ask in the EMC RecoverPoint community.
Blog: lucd.info Twitter: @LucD22 Co-author PowerCLI Reference