I have a scenario, where partyA rpc connection is not available on client side and all calls are forwarded via another corda node using flows.
Is it possible to kill hanging flows in PartyA node from inside a corda flow?
No,this is not possible. Different nodes typically belong to different entities, so allowing adminstrative access via the p2p protocoll is not supported. You need RPC access to a node to be able to kill flows.