I need to delete durable subscribers after each JMeter's test run using JMeter.
I would like to create HTTP request to the ActiveMQ Web Console as it is shown on browser WebConsole.
But I need to know:
You don't need to "generate" this value, you need to "extract" this value from the previous response using a suitable Post-Processor (CSS Selector Extractor is a good choice)
Just inspect the immediately previous response source and you will see this "secret" value there. Fetch it, store into a JMeter Variable and you should be good to go.
More information: How to Load Test CSRF-Protected Web Sites