How do I expire a timer manually/programmatically in Activiti BPMN?

I am using Activiti BPMN version 5.15. I have a user task where I attached a timer as you see at the following screenshot

How am I supposed to make the timer expire now (for testing purposes) either programmatically or manually ?

Thank you

Why don't you add a signal boundary event that points to the same output just for testing. You can send the signal to the engine via the REST API (again, just for testing). The handler can stay in place in production as nothing will ever trigger it. You can also follow the solution here which also uses a signal, but uses the signal to reset the boundary timer. The second option is more complex, but may better emulate exactly what you are asking for.