I can see pzTenantID property which is available in System-Requestor-Context(pr_sys_context) class which takes pzRequestorId as input key property. You can query this class and check the tenant id of your requestor.
Also you can identify whether the environment is a multi-tenant or not with below steps? - At the database level most of the tables contain the column pzTenantId defined as VARCHAR2(255) NOT NULL. One can verify whether tables such PR4_RULE and PR_OPERATORS contain the above column or not? - One can login as the multitenant administrator (firstname.lastname@example.org) and verify whether the Tenant Management landing page (Designer Studio > System > Tenant Management) exists or not?
1) in the application used standart settingth for Lock. For parent case Locking strategy "A case is opened (default)". For SubCases Locking strategy "Locking strategy is inherited from parent case type" and selected "Do not lock the parent case when the child case is opened";
When the subCase has Soft Lock all work good. But for true Lock not work.
2) This solution need to release the Lock for subCases when they are locked by another operators.
3) Yes. The row from the table pr_sys_locks has been deleted.
Even though the record has been deleted in the pr_sys_locks table, but there will be a memory cache on the node. So the lock has been not yet released in your case.
This needs to be investigated further by the Product engineers to confirm you the right approach to delete this record in the table and clear the memory in the node for the lock. So i suggest you to raise an SR with Global Customer Support team to investigate this issue further and provide the solution to your requirement if it is feasible.
Also i can see the internal discussions regarding this requirement and the product team is not ready to provide any way to steal lock from another user without blowing up the second requestor. So i am not sure whether your requirement will be implemented.