There are two pool settings; "Default display protocol" and "Allow users to choose protocol". Set the first one to "PCoIP" and the second one to "No". In our environment we only allow "VMware Blast". Be aware that if you restrict the pool to only allow "VMware Blast" it will still allow PCoIP connections from zero clients and pre-4.0 Horizon Clients (see page 4 of Blast Extreme Display Protocol in VMware Horizon 7: VMware Horizon 7 version 7.x).
