You can disable clustering in a Juniper SRX with the following command:
set chassis cluster disable
You can also disable clustering with this command:
set chassis cluster cluster-id 0
This goes against the way most things work inside JUNOS. Typically, if you have a numbered field, it always starts at Zero. Not the case for cluster-id. Cluster-id 1 is the first available cluster-id. If you set the cluster-id to 0, you actually end up disabling clustering altogether.
What this actually does: It zeros out the bits in NVRAM that the jrspd process looks at, effectively disabling the process.